Musannaf Ibn Abi Shayba 9:1040

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Jabir, from ‘Amir, who said: ‘Ali said: "It is not lawful for him until he shakes her with the shaking of a young she-camel." He said: And ‘Aisha said: "Until the other tastes her sweetness and she tastes his sweetness."