Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) said: "Whoever has four traits is a thorough hypocrite, and whoever has one of them has a trait of hypocrisy until he abandons it: when he speaks, he lies; when he makes a promise, he breaks it; when he makes a covenant, he violates it; and when he disputes, he becomes abusive."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18845
Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that the Messenger of Allah (peace and blessings be upon him) said: "A banner will be raised on the back of the treacherous person, and it will be said: This is the treachery of so-and-so." In the narration of Malik it is: "On the Day of Resurrection a banner will be raised on his back (proclaiming) that this is the treachery of so-and-so."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18846
Sulaym bin Amir, a man of the tribe of Himyar, narrates that there was a covenant between Sayyiduna Mu'awiyah (may Allah be pleased with him) and the Romans. Sayyiduna Mu'awiyah (may Allah be pleased with him) was advancing towards their lands so that when the term of the covenant ended he could attack them. (Meanwhile) a man came riding a horse, saying in a loud voice: "Allah is the Greatest, Allah is the Greatest! Fulfil the covenant; do not betray." The people looked, and it was Sayyiduna Amr bin Abasah (may Allah be pleased with him). Sayyiduna Mu'awiyah (may Allah be pleased with him) sent someone to him and asked (about it), and he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever has a covenant with a people should neither tighten any knot of it nor untie it until its term ends or he throws it back to them on equal terms." So Sayyiduna Mu'awiyah (may Allah be pleased with him) went back.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18847
It is narrated from Sayyiduna Abu Bakrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever unjustly kills a mu'ahad (one with whom a covenant has been made), Allah Almighty will make Paradise forbidden for him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18849
Sayyiduna Buraydah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Whenever a people break a covenant, killing becomes widespread among them; whenever indecency becomes widespread among a people, deaths become widespread among them; and whenever a people do not pay zakah, rain is withheld from them."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18850
Sayyiduna Anas (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) addressed us and said: "Whoever is not trustworthy has no faith, and whoever does not keep his promise has no religion."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18851