Musnad Ahmad 1017:100

Humaid ibn Abd al-Rahman al-Ru'asi narrated to us, my father narrated to us, from Abd al-Karim ibn Sulayt, from Ibn Buraydah, from his father, who said: When Ali proposed to Fatimah, the Messenger of Allah (peace and blessings of Allah be upon him) said: "A wedding must have a feast." Sa'd said: "I will provide a ram." And another person said: "I will provide such and such amount of corn."