Musnad Ahmad 1156:68

'Abd al-Rahman ibn Mahdi narrated to us, he said: Salam ibn Abi Muti' narrated to us, from 'Uthman ibn 'Abd Allah ibn Mawhab, he said: I entered upon Umm Salamah, and she brought out to us a hair from the hair of the Messenger of Allah, may Allah bless him and grant him peace, dyed with henna and katam.