Musnad Ahmad 1167:29

Ibn Numayr narrated to us, he said: Hisham narrated to us, from his father, from Asma bint Abi Bakr, she said: My mother came to me while she was a polytheist during the time of the Quraysh when they made a treaty. So I came to the Prophet, may Allah bless him and grant him peace, and said: "O Messenger of Allah, my mother has come to me and she is desirous (of my favor), should I maintain ties with her?" He said: "Yes, maintain ties with your mother."