Evidence from Qur'an and Sunnah
 

Manners towards non-Muslims:

Treating them kindly:

Allah says:

]لا يَنْهَاكُمُ اللَّهُ عَنِ الَّذِينَ لَمْ يُقَاتِلُوكُمْ فِي الدِّينِ وَلَمْ يُخْرِجُوكُم مِّن دِيَارِكُمْ أَن تَبَرُّوهُمْ وَتُقْسِطُوا إِلَيْهِمْ إِنَّ اللَّهَ يُحِبُّ الْمُقْسِطِين. إِنَّمَا يَنْهَاكُمُ اللَّهُ عَنِ الَّذِينَ قَاتَلُوكُمْ فِي الدِّينِ وَأَخْرَجُوكُم مِّن دِيَارِكُمْ وَظَاهَرُوا عَلَى إِخْرَاجِكُمْ أَن تَوَلَّوْهُمْ وَمَن يَتَوَلَّهُمْ فَأُوْلَئِك هُمُ الظَّالِمُونَ[
(الممتحنة: 8 - 9)

This means: “Allah does not forbid you to deal justly and kindly with those who fought not against you on account of religion and did not drive you out of your homes. Verily, Allah loves those who deal with equity. It is only as regards those who fought against you on account of religion, and have driven you out of your homes, and helped to drive you out, that Allah forbids you to befriend them. And whosoever will befriend them, then such are the Zhalimun (wrong-doers those who disobey Allah).”
(60, Al-Mumtahinah: 8 - 9)

Allah says:

]وَإِنْ أَحَدٌ مِّنَ الْمُشْرِكِينَ اسْتَجَارَكَ فَأَجِرْهُ حَتَّى يَسْمَعَ كَلاَمَ اللّهِ ثُمَّ أَبْلِغْهُ مَأْمَنَه[ (التوبة: 6)

This means: “And if anyone of the Mushrikun (polytheists, idolaters, pagans, disbelievers in the Oneness of Allah) seeks your protection then grant him protection, so that he may hear the Word of Allah (the Qur'an), and then escort him to where he can be secure.” (9, At-Tawbah: 6)

Allah says:

]وَطَعَامُ الَّذِينَ أُوتُواْ الْكِتَابَ حِلٌّ لَّكُمْ وَطَعَامُكُمْ حِلُّ لَّهُم[
(المائدة: 5)

This means: “The food (slaughtered cattle, eatable animals, etc.) of the people of the Scripture (Jews and Christians) is lawful to you and yours is lawful to them.” (5, Al-Ma’idah: 5)

The Prophet (peace be upon him) said:

“Beware, if anyone wrongs a contracting man, or diminishes his right, or forces him to work beyond his capacity, or takes from him anything without his consent, I shall plead for him on the Day of Judgment.” (Reported by Muslim)

Not to take them as patrons:

Allah says:

]يَا أَيُّهَا الَّذِينَ آمَنُواْ لاَ تَتَّخِذُواْ الْكَافِرِينَ أَوْلِيَاء مِن دُونِ الْمُؤْمِنِين[
(النساء: 144)

This means: “O you who believe! Take not for Awliya' (protectors or helpers or friends) disbelievers instead of believers.” (4, An-Nisa’: 144)

Allah says:

]لا تَجِدُ قَوْمًا يُؤْمِنُونَ بِاللَّهِ وَالْيَوْمِ الآخِرِ يُوَادُّونَ مَنْ حَادَّ اللَّهَ وَرَسُولَهُ وَلَوْ كَانُوا آبَاءهُمْ أَوْ أَبْنَاءهُم أَوْ إِخْوَانَهُمْ أَوْ عَشِيرَتَهُمْ[
(المجادلة: 22)

This means: “You (O Muhammad SAW) will not find any people who believe in Allah and the Last Day, making friendship with those who oppose Allah and His Messenger (Muhammad SAW), even though they were their fathers, or their sons, or their brothers, or their kindred (people).” (58, Al-Mujadalah: 22)

Not to emulate non-Muslims:

The Prophet (peace be upon him) said:

“He who copies any people is one of them.”
(Reported by Abu Dawud)

The Prophet (peace be upon him) said:

“Do the opposite of what the pagans do. Keep the beards and cut the moustaches short.” (Reported by Al-Bukhari and Muslim)

Sitting and road manners:

Allah says:

]وَإِذَا جَاءكَ الَّذِينَ يُؤْمِنُونَ بِآيَاتِنَا فَقُلْ سَلاَمٌ عَلَيْكُم[
(الأنعام: 54)

This means: “When those who believe in Our Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) come to you, say: "Salamun 'Alaykum" (peace be on you).” (6, Al-An`am: 54)

Allah says:

]يَا أَيُّهَا الَّذِينَ آمَنُوا إِذَا قِيلَ لَكُمْ تَفَسَّحُوا فِي الْمَجَالِسِ فَافْسَحُوا يَفْسَح اللَّهُ لَكُمْ وَإِذَا قِيلَ انشُزُوا فَانشُزُوا يَرْفَعِ اللَّهُ الَّذِينَ آمَنُوا مِنكُمْ وَالَّذِينَ أُوتُوا الْعِلْمَ دَرَجَاتٍ وَاللَّهُ بِمَا تَعْمَلُونَ خَبِير[
(المجادلة: 11)

This means: “O you who believe! When you are told to make room in the assemblies, (spread out and) make room. Allah will give you (ample) room (from His Mercy). And when you are told to rise up [for prayers, Jihad (holy fighting in Allah's Cause), or for any other good deed], rise up. Allah will exalt in degree those of you who believe, and those who have been granted knowledge. And Allah is Well-Acquainted with what you do.” (58, Al-Mujadalah: 11)

Allah says:

]وَعِبَادُ الرَّحْمَنِ الَّذِينَ يَمْشُونَ عَلَى الأرْضِ هَوْنًا وَإِذَا خَاطَبَهُمُ الْجَاهِلُونَ قَالُوا سَلامًا[ (الفرقان: 63)

This means: “And the slaves of the Most Beneficent (Allah) are those who walk on the earth in humility and sedateness, and when the foolish address them (with bad words) they reply back with mild words of gentleness.” (25, Al-Furqan: 63)

Allah says:

]قُل لِّلْمُؤْمِنِينَ يَغُضُّوا مِنْ أَبْصَارِهِم[
(النور: 30)

This means: “Tell the believing men to lower their gaze (from looking at forbidden things).” (24, An-Nur: 30)

Allah says:

]وَإِذَا حُيِّيْتُم بِتَحِيَّةٍ فَحَيُّواْ بِأَحْسَنَ مِنْهَا أَوْ رُدُّوهَا[
(النساء: 86)

This means: “When you are greeted with a greeting, greet in return with what is better than it, or (at least) return it equally.” (4, An-Nisa’: 86)

  Allah says:

]وَالْمُؤْمِنُونَ وَالْمُؤْمِنَاتُ بَعْضُهُم أَوْلِيَاء بَعْضٍ يَأْمُرُونَ بِالْمَعْرُوفِ وَيَنْهَوْنَ عَنِ الْمُنكَر[ (التوبة: 71)

This means: “The believers, men and women, are Awliya' (helpers, supporters, friends, protectors) of one another, they enjoin (on the people) Al-Ma'ruf (i.e. Islamic Monotheism and all that Islam orders one to do), and forbid (people) from Al-Munkar (i.e. polytheism and disbelief of all kinds, and all that Islam has forbidden).” (9, At-Tawbah: 71)

Abu Sa`id Al-Khudri (may Allah be pleased with him) narrated that Allah's Prophet (peace be upon him) said:

“Avoid sitting on the streets. They (his Companions) said: Allah's Messenger, there is no other help (but to sit here as we) to hold our meetings and discuss matters there. Thereupon, Allah's Messenger (peace be upon him) said: If you have to sit there, then fulfill the rights of the street. They said: What are these rights? Thereupon, he said: Keeping the eye downward (so that you may not stare at women), refraining from doing some harm to others and exchanging greetings (saying As-Salamu `Alaykum) and commanding the good and forbidding the evil.”
(Reported by Al-Bukhari and Muslim)

Samurah (may Allah be pleased with him) narrated:

“When we came to the Prophet (peace be upon him), each one would sit down where there was room.” (Reported by At-Tirmidhi)

The Prophet (peace be upon him) said:

“Do not ask someone to give up his seat in order to take it, but make accommodation wide and sit at ease.”
(Reported by Al-Bukhari and Muslim)

The Prophet (peace be upon him) said:

“It is not permissible for a person to sit between two people without their permission.” (Reported by Abu Dawud)

The Prophet (peace be upon him) said:

“If someone leaves his seat (for one reason or another) and returns to it, he is better entitled to it.” (Reported by Muslim)

Abu Barzah (may Allah be pleased with him) narrated:

The Messenger of Allah (peace be upon him) would supplicate before leaving an assembly thus, “O Allah, You are free from every imperfection; all praise is for You. I testify that there is no true god except You, I ask Your forgiveness and turn to You in repentance.” A man once said to him: O Messenger of Allah! You have spoken such words that you have never uttered before. He said, “It is an expiation of that which goes on in the assembly.”
(Reported by Abu Dawud)

Good manners when traveling:

Allah says:

]يَا عِبَادِيَ الَّذِينَ آمَنُوا إِنَّ أَرْضِي وَاسِعَةٌ فَإِيَّايَ فَاعْبُدُون[
(العنكبوت: 56)

This means: “O My slaves who believe! Certainly, spacious is My earth. Therefore worship Me (Alone).” (29, Al-`Ankabut: 56)

Allah says:

]لِتَسْتَوُوا عَلَى ظُهُورِهِ ثُمَّ تَذْكُرُوا نِعْمَةَ رَبِّكُمْ إِذَا اسْتَوَيْتُمْ عَلَيْهِ وَتَقُولُوا سُبْحان الَّذِي سَخَّرَ لَنَا هَذَا وَمَا كُنَّا لَهُ مُقْرِنِينَ. وَإِنَّا إِلَى رَبِّنَا لَمُنقَلِبُون[
(الزخرف: 13 - 14)

This means: “When you mount thereon, and say: "Glory to Him who has subjected this to us, and we could never have it (by our efforts). And verily, to Our Lord we indeed are to return!” (43, Az-Zukhruf: 13 - 14)

Ibn `Umar (may Allah be pleased with him) narrated:

“The Messenger of Allah (peace be upon him) recited: Allah is the Greatest (three times) when he rode a camel setting for a journey. Then, he would say: Glory to Him who has subjected this to us, and we could never have it (by our efforts). And verily, to Our Lord we indeed are to return!. O our Lord, I ask You for virtue and piety, and for the deed which may please You. O our Lord, comfort this journey for us, and fold up its length. O our Lord, You are the Companion in the journey, and the Guardian of our families. O Allah I seek refuge with You from hardships of journey, gloominess of appearance and finding of evil changes in property and family. And on his return he said the same thing, but added: We are returning, repentant, worshipping our Lord, and praising Him.”
(Reported by Muslim)

The Prophet (peace be upon him) used to bid farewell saying:

“I entrust Allah with your religion, your trust and your last deeds.” (Reported by At-Tirmidhi)

The Messenger of Allah (peace be upon him) said:

“Traveling is a piece of torture; it deprives a traveler of his sleep, food and drink. When a person has accomplished his purpose of journey, he should hurry up in returning to his family.”
(Reported by Al-Bukhari and Muslim)

The Messenger of Allah (peace be upon him) said:

“If anyone of you was away from home for a long period, he should not return home at night.”
(Reported by Al-Bukhari and Muslim)

The Messenger of Allah (peace be upon him) said:

“It is not lawful for a woman to take a journey for a day and a night unless she is accompanied by a male Mahram (umarriageable person).” (Reported by Al-Bukhari and Muslim)

The Prophet (peace be upon him) said:

“When you enter your home in the night, Wait so that the lady whose hair is unkempt may comb her hair and that the lady whose husband has been away may shave her pubic hair.” (Reported by Al-Bukhari)