It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) said: "Moving the finger in the prayer is like a spear against Satan."
(b) Mujahid (may Allah have mercy on him) said: A man's moving his finger in the tashahhud of the prayer is a hammer against Satan.
Muhammad bin Umar al-Waqidi alone narrated the hadith of Ibn Umar, and he is not strong.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2788