Reference: http://mufti.af.org.sa/ar/content/التسبيح-بالأصابع-أكمل-وأفضل
Question: I am asking about the [gadgets which are worn as] rings on the index finger – which have a number counter on them. The intention behind using them is to make use of the time by engaging in tasbeeh. So what is the Sharee’ah-based ruling regarding [using] it, and may Allaah reward you?
Response: It may be permissible, however, counting the tasbeeh [سبحان الله], the takbeer [الله أكبر] and the tahmeed [الحمد لله] on your fingers is more complete [in accordance with the Sunnah] and best – because they (the fingers) will be asked[1] and questioned [about it on the Day of Judgement].
Footnote:
[1]
«Count on your fingers, for they will be asked, and will be made to speak.»
