When the people of Mecca sent ransoms for their captives, Zaynab sent property to ransom Abu al-As, including a necklace of hers that had belonged to Khadijah. Khadijah had given it to her when she married Abu al-As.She said, when the Messenger of Allah ﷺ saw the necklace, he was deeply moved with tenderness for her, and he said, "If you see fit to release her captive to her and return to her what is hers, then do so."They replied, "Yes."The Messenger of Allah ﷺ had taken a pledge from Abu al-As, or made an agreement with him, that he would let Zaynab go to him. So the Messenger of Allah ﷺ sent Zayd bin Haritha along with a man from the Ansar and instructed them, "Stay in the valley of Yajaj until Zaynab passes by you, then accompany her and bring her back."
لما بعث أهل مكة في فداء أسراهم بعثت زينب في فداء أبي العاص بمال، وبعثت فيه بقلادة لها، كانت عند خديجة، أدخلتها بها على أبي العاص قالت: فلما رآها رسول الله ﷺ رق لها رقة شديدة، وقال: أرأيتم أن تطلقوا لها أسيرها، وتردوا الذي لها؟ فقالوا: نعم، وكان رسول الله ﷺ أخذ عليه- أو وعده- أن يخلي سبيل زينب إليه، وبعث رسول الله ﷺ زيد بن حارثة ورجلا من الأنصار، فقال: كونوا ببطن (يأجج) حتى تمر بكما زينب، فتصحباها حتى تأتيا بها.
This was narrated by Abu Dawud (2692), Ahmad (26362), Ibn Jarud (1090), Hakim (3/23 and 236, 4/44–45), and Bayhaqi, all of them through various routes from Muhammad bin Ishaq, who said, "Yahya bin Abbad bin Abdullah bin Zubayr narrated to me, from his father Abbad, from Ayesha, the wife of the Prophet ﷺ," and he related it. The wording given is that of Abu Dawud, and it is also found in Sirat bin Hisham (1/653). Its chain is hasan because of Muhammad bin Ishaq, for his hadith is hasan when he states his source explicitly. Hakim said, "It is a sahih hadith meeting the criteria of Muslim."Among others who were also released without ransom was Muttalib bin Hantab bin Harith bin Ubayda bin Umar bin Makhzum. He belonged to some of the Banu Harith bin Khazraj, who left him in their custody until they released him, and he rejoined his people.Also Sayfi bin Abu Rifa from Banu Makhzum, who was left in the custody of his captors. When no one came to ransom him, they made him pledge that he would send them his ransom, and they then released him, but he never fulfilled anything of it for them.Also Abu Azza, who was Amr bin Abdullah bin Uthman bin Uhayb bin Hudhafa bin Jumah. He was needy and had daughters, so he spoke to the Messenger of Allah ﷺ and said, "Messenger of Allah, you know well what wealth I have, and I am truly in need and burdened with dependents, so show me favor." So the Messenger of Allah ﷺ showed him favor, taking from him a pledge that he would not support anyone against him. Concerning this, Abu Azza said in praise of the Messenger of Allah ﷺ,Who will convey from me to the Messenger, Muhammad, that you are truth, and the Sovereign is praised. You are a man who calls to truth and guidance, over you, from Allah the Mighty, there is a witness.Sirat bin Hisham (1/659–660)