Musnad Ahmad 938:11

Sufyan narrated to us, from ‘Amr, from Tawus, from Hujr al-Madari, from Zayd ibn Thabit: "That the Prophet, peace and blessings of Allah be upon him, made the *‘umra* (life-gift) for the heir." And he said once: "He decreed the *‘umra*."