Musnad Ahmad 33:137

Hushaym narrated to us, from Husayn, from Salim ibn Abi al-Ja‘d, from Jabir ibn ‘Abd Allah, who said: A boy was born to a man among us, and he named him al-Qasim. We said: We will not call you by his kunya (patronymic) until we ask the Prophet, peace and blessings of Allah be upon him. So we mentioned it to him, and he said: "Name yourselves with my name, but do not use my kunya, for I was only sent as a distributor (qasim) among you."