It was the practice of the Prophet (peace and blessings be upon him):
"He (peace and blessings be upon him) would make a gesture during the prayer (when the need arose)."
Hadith Referenceصحیح الجامع الصغیر / حرف الكاف / 4957
Hadith Gradingالألبانی:صحيح
Hadith Takhrij[حم] عن أنس. الروض ٨٥، صحيح أبي داود ٨٧١.