Musnad Abu Ya'la al-Mawsili 109:266

Kamil narrated to us, Layth ibn Sa'd narrated to us, he said: Abu al-Zubayr narrated to me, from Jabir ibn 'Abd Allah, that he informed him that Hatib ibn Abi Balta'ah wrote to the people of Makkah mentioning that the Messenger of Allah (may Allah bless him and grant him peace) intended to raid them. The Messenger of Allah (may Allah bless him and grant him peace) was directed to the woman who had the letter with her. He sent for her, and her letter was taken from her head. He said, "O Hatib, have you done this?" He said, "Yes. As for me, I did not do it out of deceit toward the Messenger of Allah (may Allah bless him and grant him peace), nor out of hypocrisy. I knew that Allah would make His Messenger victorious and complete His affair for him. However, I was among them, and my mother was with them, so I wanted to take her (as a means of protection) among them." 'Umar said to him, "Shall I strike the neck of this one?" He (the Prophet) said, "Would you kill a man from the people of Badr? And what do you know? Perhaps Allah has looked upon the people of Badr and said, 'Do what you wish.'"