Rasulullah (sallallahu alayhi wasallam) is reported to have said: Whoever recites the following 100 times after Jumu’ah Salah on Friday, 100 000 of the reciter’s sins will be forgiven & in addition 24,000 of his/her parents’ sins will also be forgiven:
ِ سُبْحَانَ اللّٰهِ العَظِیْمِ وَ بِحَمْدِه
Subhanallahil azeemi wa bi hamdihi. (Ibnus-Sunni)
Sayyiduna ‘Abdullah ibn ‘Umar (radiyallahu’anhuma) reports that Rasulullah (sallallahu’alaihi wasallam) said: “Whoever recites: ‘Subhanallahi wa bi hamdihi’ will receive one hundred and twenty four thousand rewards.” (Tabarani)
There are other Hadiths also that encourage this tasbih.When reciting it, one should aspire for all the rewards that are promised.
Source and for detailed referencing & authentication, please refer to: https://hadithanswers.com/a-beautiful-tasbih-for-after-jumuah-salah/