During the treaty of Hudiabiya, Sohail Ibn Umer was representing the disbelievers in negotiating with the Holy Prophet (S). When it was time for drawing up the treaty and the signatures were yet to be affixed, Jundal the son of Sohail left the pack of disbelievers and went to the Muslims. Seeing that he was attracted to the Muslims, the Quraish chained his legs but he escaped with the chains intact. He went away with the Muslims and began to behave like one. When his father saw this, he came to his son and gave him a resounding slap. Then he told the Holy Prophet (S), “O Muhammad! This (treaty) is the first step of reconciliation between you and us and as per its terms you have to surrender my son to me.”
The Holy Prophet (S) agreed to it and surrendered Jundal to his Kafir father, but upon the condition that he would be protected and not harmed. Sohail Ibn Umar agreed to this condition. When it was time to hand over Jundal to the disbelievers, Jundal protested, “O Muslims! I have become a Muslim! How will I return amongst the polytheists?”
The Holy Prophet (S) told him,
“Go! But have patience. Allah will provide ease to you in this way only. We cannot go against the terms of the treaty.”
Sohail caught his son’s hand and led him away. He did not remain true to his promise and tortured his son very much.
This incident proves the importance of the fulfillment of a promise. The same incident is mentioned in the exegesis of Surah al-Fath in Tafsīr Minhaj us-Sādiqīn.