Ash-Shaykh Dr. Abdul-'Azeez Al-Fawzaan discusses the ruling regarding using
Question: Umm 'Abdir-Rahman Al-Britaaniyyah (a British woman) asks two questions. The first is the ruling regarding using al-Misbahah (Thikr beads) in order to make Thikr (words to remember Allah).
Answer: There is no problem with that. It is permissible to use them, regardless of whether that is for having them with you or actually using them for Tasbeeh (saying Subhanallah; words to glorify and remember Allah), there is no harm in that. The basic ruling regarding that is permissibility. However, what is best and what is Sunnah is to make Tasbeeh with the two hands. And also between the two hands the right hand is better for glorifying Allah than the left, but to use both hands, there's no problem with that - meaning using both hands together to make Thikr. And the Prophet (peace and blessing be upon him), as is confirmed from him in the authentic hadeeth, he used to count the the words of Tasbeeh on his hand (i.e. his fingers) - peace and blessing be upon him. So this is the Sunnah.
Then, also my brother, if you count the words of Tasbeeh on your fingers, your hand will testify for you tomorrow (i.e. on the Day of Judgment) however much Tasbeeh you did using them. So this is what is preferred and most perfect. However, if it happens to be that a person says, "By Allah, I always forget or loose count, or maybe I end up counting less than the number I want on my hands and stop before I finish. And these beads that I use have 100 beads on the string, or 300, or whatever, and I use it to count my Tasbeeh." We say the basic ruling regarding that is that it is permissible. Even though it is contrary to the Sunnah. Yes.