Musnad Abu Ya'la al-Mawsili 147:4

Abu Khaythama narrated to us, Yazid narrated to us, Sadaqah ibn Musa informed us, from Abu Imran al-Jawni, from Anas, that the Messenger of Allah (may Allah bless him and grant him peace) set a time limit for us regarding the trimming of the mustache, the clipping of the nails, and the shaving of the pubic hair, that it should not be left for more than forty days.