Musnad Ahmad 232:2

Muhammad ibn Ja‘far narrated to us, he said: Kahmas narrated to us, he said: I heard Sayyar ibn Manzur al-Fazari, he said: My father narrated to me, from Bahisah, she said: My father asked permission to enter upon the Prophet, may Allah bless him and grant him peace, so he entered between him and his shirt, and he mentioned its meaning.