Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Ja'far that the Holy Prophet (peace and blessings be upon him) had his head shaved during Umrah.

Hazrat Abdur Rahman bin Amr bin Sahl narrates that I saw Hazrat Uthman when he came to Makkah Mukarramah and we were with him. He did not untie any knot there until he returned, and he did not add anything to the Tawaf of the House of Allah, and he performed Sa’i between Safa and Marwah, and had his blessed head shaved.

Hazrat Qasim had his head shaved during Umrah.

Ibrahim says that when a person performs Umrah who has not performed Hajj before, then if he wishes, he may shave his head, and if he wishes, he may shorten his hair.

Ibrahim states that the Companions used to prefer that a person performing Hajj or Umrah for the first time should have his head shaved.