Musnad Ahmad 5:39

Sufyan narrated to us, from ‘Amr, who said: Hasan ibn Muhammad ibn ‘Ali informed me, ‘Ubaydullah ibn Abi Rafi’ informed me—and he said once: that ‘Ubaydullah ibn Abi Rafi’ informed him—that he heard ‘Ali saying: The Messenger of Allah (ﷺ) sent me, along with az-Zubayr and al-Miqdad, and said: "Go until you reach Rawdat Khakh, for there is a woman there with a letter; take it from her." So we set off, our horses galloping with us, until we reached the meadow. There we found the woman and said: "Produce the letter." She said: "I have no letter with me." We said: "You will either produce the letter, or we will strip your clothes." He said: So she took the letter out of her hair braid. We took the letter and brought it to the Messenger of Allah (ﷺ). It contained: "From Hatib ibn Abi Balta’ah to some of the polytheists in Makkah, informing them of some of the affairs of the Messenger of Allah (ﷺ)." The Messenger of Allah (ﷺ) said: "O Hatib, what is this?" He said: "Do not be hasty with me. I was a man who was an ally to Quraysh, and I was not one of their own. Those who are with you from the Emigrants have relatives there who protect their families in Makkah. Since I lacked that lineage among them, I wanted to do them a favor so that they might protect my relatives through it. I did not do this out of disbelief, nor apostasy from my religion, nor out of satisfaction with disbelief after Islam." The Messenger of Allah (ﷺ) said: "He has told you the truth." ‘Umar said: "Let me strike the neck of this hypocrite." He (the Prophet) said: "He has witnessed Badr. And what do you know? Perhaps Allah looked upon the people of Badr and said: 'Do what you wish, for I have forgiven you.'"