Wa'il bin Hujr (may Allah be pleased with him) said: I thought to myself that I would certainly watch the prayer of the Messenger of Allah (peace and blessings be upon him), how he (peace and blessings be upon him) prays. He mentioned the complete hadith. In it is: He (peace and blessings be upon him) sat with his left foot laid flat, placed his palm on his left thigh and knee, and placed his right elbow on his right thigh. Then he closed three of his fingers and formed a ring, then raised the index finger; he (peace and blessings be upon him) kept moving it, supplicating with it.
(b) It is possible that what is meant by moving it is pointing with the finger, not moving it continuously. In this way this hadith would agree with the narration of Ibn al-Zubayr (may Allah be pleased with them both). And Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2787