Bukayr bin 'Abdullah bin al-Ashj بكير بن عبد الله بن الأشج · The Book on Salat (Prayer)

"I passed by Allah's Messenger (S) while he was performing Salat, so I said greeted him with Salam, and he returned it by making signals." He said: "I do not know except that he said: 'He indicated with his finger.'"