Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.106.
Section : Counting on One’s Fingers is Better than Counting Beads.
Yusairah reported that the Prophet, peace be upon him, commanded them (the emigrant women) to be regular in remembering Allah by saying, “Allah is the most great,” “Glory be to Allah, the Holy,” and “There is no God but Allah,” and never to be forgetful of Allah and His Mercy, and to count them on their fingers, for the fingers will be questioned and will speak. (Reported in the Sunan and by Al-Hakim with a sound chain of authorities)
Abdallah b. ‘Amr b. al-‘As reported, “I saw the Prophet, peace be upon him, counting the glorifications of Allah on his right hand’s fingers.” (Reported in the Sunan)