Musnad Abu Ya'la al-Mawsili 108:108

Uthman ibn Abi Shaybah narrated to us, Abu Khalid al-Ahmar Sulayman ibn Hayyan narrated to us, from Thawr ibn Yazid, from Abu al-Zubayr, from Jabir, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Greeting with one finger, gesturing with it, is the action of the Jews."