Mus'ab bin Sa'd reported that his father told him that he had been in the company of Allah's Messenger (ﷺ) that he said: Is one amongst you powerless to get one thousand virtues every day. Amongst those who had been sitting there, one asked: How one amongst us can get one thousand virtues every day? He said: Recite: "Hallowed be Allah" one hundred times for (by reciting them) one thousand virtues are recorded (to your credit) and one tbousand vices are blotted out.
Hadith Referenceصحيح مسلم / كتاب الذكر والدعاء والتوبة والاستغفار / 2698
Mus'ab bin Sa'd narrates from his father that the Prophet Muhammad (peace be upon him) said: "Can any person not do this, that he earns one thousand good deeds every day?" So one of those sitting with the Prophet (peace be upon him) asked: How can a person earn one thousand good deeds every day? The Prophet (peace be upon him) replied: "He should recite Subhan Allah one hundred times, and recite Allahu Akbar one hundred times, and this will become one thousand good deeds."
Shaykh Muhammad Ibrahim bin Basheer
Benefit: In this hadith, the virtue of saying "Subhan Allah" and "Allahu Akbar" is being mentioned. From this hadith, it is understood that by saying "Subhan Allah" one hundred times or "Allahu Akbar" one hundred times, one receives a thousand good deeds. It is narrated from Sayyiduna Abu Malik Ash'ari radi Allahu anhu that the Messenger of Allah sallallahu alayhi wa sallam said: Purity is half of faith, and "Alhamdulillah" fills the scale, and saying "Subhan Allah walhamdulillah" fills the scale, or he said: fills what is between the heavens and the earth. (Sahih Muslim: 223)
In the explanation of this hadith, the Qur'an commentator Hafiz Salahuddin Yusuf rahimahullah writes: Also, the virtues and reward of the aforementioned remembrances (adhkar) are mentioned, that if these words were given a physical form, the scale would fill the distance between the heavens and the earth. This, in fact, is a description of the vastness of Allah Ta'ala's grace and bounty and His boundless mercy. (Riyadh as-Salihin: 2/342)
Source: Musnad al-Humaydi: Commentary by Muhammad Ibrahim bin Bashir, Page: 80