Safwan bin Umayya was a deadly enemy of Islam. When Makkah was conquered, he ran away to Jeddah with the intention of going to Yemen. Umir ibn Wahab came to the Holy Prophet and told him about Safwan. The Holy Prophet gave him his turban and said, "This is a sign of the guarantee of his safety." Umir went to Safwan with the turban and told him that he had no cause to run away for his safety had been guaranteed. When be came to see the Holy Prophet, he said, "Have you given me amen (safety)?" The Holy Prophet said, "Yes, it is true." Abu Rafey, a slave, came to Medinah as an ambassador of the Quraish. When he saw the Holy Prophet, the truth of Islam dawned on him and he said, "O Messenger of God! I shall never go back to the unbelievers." The Holy Prophet said, "I can neither breach the contract, nor keep the ambassadors with me. If you feel the same way when you go there, you can come back." He went back and embraced Islam.
In the treaty of Hudaibiyah, one of the conditions was that if any Muslim went to Medinah from Makkah, he would be returned on demand. When the Treaty was being written, Abu Jandal escaped from the prison of the Makkans in chains. All the Muslims were shocked to see him in this condition, but the Holy Prophet said to him, "O Abu Jandal! Be patient, we cannot break the promise. God will very soon find a way for you." He was returned to the people of Makkah. Two companions of the Holy Prophet, Hazifa bin al-Yaman and Abu Husail, while coming from Makkah, were caught by the unbelievers. The Makkans insisted that they should not go to Muhammad but the two companions refused. At last they were released on the condition that they would not participate in the battle (of Badr) on behalf of the Muslims. They came to the Holy Prophet and told him the whole story. It was a severe test of their truthfulness. The Muslims were very few and needed more men to fight against the unbelievers. The addition of two men would have made a lot of difference to them but the Holy Prophet said, "Both of you must go back; we will keep the promise under all circumstances. We need only the help of God."
Muhammad always kept his promises and contracts at all costs even with his enemies, and never broke his word. He preached the Qur'an and practiced what he taught to other people in obedience to the Commandment of God
Abdullah ibn Abdul Hamsa reported that he bought something from God's Messenger before he received his prophetic commission, and as there was something still due to Muhammad, he promised that he would bring it to his place. But Hamsa forgot about it and remembered three days later. He went to that place and found God's Messenger there waiting for him. The Prophet said, "You have caused me great trouble and inconvenience. I have been here three days waiting for you." Abdullah ibn Amir reported that his mother called him one day when God's Messenger was sitting in their house, saying, "Come here and I shall give you something." God's Messenger asked her what she intended to give him; she replied that she intended to give him some dates. He said, "If you were not to give him anything, a lie would have been recorded against you.
Abu Juhaifa said, I saw God's Messenger as a fair-skinned man who had become gray-haired. Al-Hasan ibn Ali resembled him. He ordered that thirteen young she-camels should be given to us and we went to receive them, but news of his death reached us before they had been given to us. Then when Abu Bakr became Caliph, he said, "If anyone has received a promise from God's Messenger, let him come." So I got up, went to him and told him of the promise and he ordered that the camels should be given to me."