Musnad Abu Ya'la al-Mawsili 3:137

Ishaq ibn Isma'il narrated to us, Ishaq ibn Sulayman al-Razi narrated to me, from Abu Sinan, from 'Amr ibn Murrah, from Abu al-Bakhtari, from al-Harith, from 'Ali, who said: When the Messenger of Allah intended [to go to] Makkah, he sent word to some of his companions that he intended Makkah, among them was Hatib ibn Abi Balta'ah. It spread among the people that he intended Hunayn. Hatib wrote to the people of Makkah that the Messenger of Allah (may Allah bless him and grant him peace) intends you. The Messenger of Allah (may Allah bless him and grant him peace) was informed of this. He sent me and Abu Marthad—and there was no man with us except that he had a horse—and said: "Go to Rawdat Khakh, for you will meet a woman there who has a letter, so take it from her." We set off until we saw her in the place the Messenger of Allah (may Allah bless him and grant him peace) had mentioned. We said to her: "Bring out the letter." She said: "I do not have a letter with me." We placed her belongings down and searched them, but we did not find it in her belongings. Abu Marthad said: "Perhaps there is no letter with her." We said: "The Messenger of Allah (may Allah bless him and grant him peace) did not lie, and we did not lie." We said to her: "Either you bring it out, or we will strip you." She said: "Do you not fear Allah? Are you not Muslims?" We said: "Either you bring it out, or we will strip you." 'Amr ibn Murrah said: She brought it out from her waist-wrapper. Habib ibn Abi Thabit said: She brought it out from her private parts. We brought it to the Prophet (may Allah bless him and grant him peace), and it was a letter from Hatib ibn Abi Balta'ah. 'Umar stood up and said: "O Messenger of Allah, he has betrayed Allah and betrayed His Messenger. Give me permission to strike his neck." The Messenger of Allah (may Allah bless him and grant him peace) said: "Has he not witnessed Badr?" They said: "Yes, O Messenger of Allah." 'Umar said: "Yes, but he has broken his covenant and aided your enemies against you." The Messenger of Allah (may Allah bless him and grant him peace) said: "Perhaps Allah has looked upon the people of Badr and said: 'Do what you wish.'" 'Umar’s eyes overflowed with tears, and he said: "Allah and His Messenger know best." The Messenger of Allah (may Allah bless him and grant him peace) sent for Hatib and said: "What compelled you to do what you did?" He said: "O Messenger of Allah, I was a man who was an ally among the Quraysh, and my family and wealth were there, and there was no one among your companions except that he had someone in Makkah to protect his family and wealth. So I wrote to them regarding that. By Allah, O Messenger of Allah, I am a believer in Allah and His Messenger." The Messenger of Allah (may Allah bless him and grant him peace) said: "Hatib has spoken the truth, so do not say anything about Hatib except good." Habib said: Then Allah revealed: "O you who have believed, do not take My enemies and your enemies as allies, extending to them affection" [Al-Mumtahanah].