Hadith: As we were with the Messenger of Allah (may Allah's peace and blessings be upon him), he asked: @"Is anyone of you unable to earn a thousand good deeds every day?"* One of those present asked: How can one earn a thousand good deeds? He replied: "He glorifies Allah a hundred times, a thousand good deeds will be recorded for him, or a thousand sins will be erased from his record."

عَنْ سَعْدِ بنِ أبي وَقَّاصٍ رَضيَ اللهُ عنه قَالَ:
كُنَّا عِنْدَ رَسُولِ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، فَقَالَ: «أَيَعْجِزُ أَحَدُكُمْ أَنْ يَكْسِبَ، كُلَّ يَوْمٍ أَلْفَ حَسَنَةٍ؟» فَسَأَلَهُ سَائِلٌ مِنْ جُلَسَائِهِ: كَيْفَ يَكْسِبُ أَحَدُنَا أَلْفَ حَسَنَةٍ؟ قَالَ: «يُسَبِّحُ مِائَةَ تَسْبِيحَةٍ، فَيُكْتَبُ لَهُ أَلْفُ حَسَنَةٍ، أَوْ يُحَطُّ عَنْهُ أَلْفُ خَطِيئَةٍ».
[صحيح] - [رواه مسلم] - [صحيح مسلم: 2698]

Sa‘d ibn Abi Waqqās (may Allah be pleased with him) reported:
As we were with the Messenger of Allah (may Allah's peace and blessings be upon him), he asked: "Is anyone of you unable to earn a thousand good deeds every day?" One of those present asked: How can one earn a thousand good deeds? He replied: "He glorifies Allah a hundred times, a thousand good deeds will be recorded for him, or a thousand sins will be erased from his record."
[Authentic hadith] - [Narrated by Muslim] - [Sahih Muslim - 2698]

Explanation

The Prophet (may Allah's peace and blessings be upon him) asked his Companions: Is it not possible for one of you to gain a thousand rewards each day?! One of those present said: How can a person earn a thousand good deeds in a single day so easily? He said: He says: "Subhānallāh" (glory be to Allah) a hundred times, and a thousand good deeds will be recorded for him because each good deed is multiplied tenfold, or a thousand sins will be erased from his record.

Benefits from the Hadith

1. Encouragement toward virtues, for they are the ladder to acts of obedience.
2. The virtue of glorifying Allah and remembering Him, and that this simple act, which costs a person nothing, brings a great and immense reward.
3. The Companions' eagerness to hasten toward good deeds without delay.
4. Good deeds are multiplied tenfold, as Allah Almighty says: {Whoever comes with a good deed will be rewarded tenfold.} [Surat al-An‘ām: 160] This is the minimum level of multiplication; however, it has also been reported up to seven hundred times.
5. In some narrations, the word "or" in the phrase “or a thousand sins will be erased” is replaced with "and". Al-Qāri explained: The conjunction 'and' can sometimes carry the meaning of 'or', so there is no contradiction between the two versions. The meaning could be that whoever says it, a thousand good deeds are written for him, and if he has sins, then some are erased and some rewards are gained. It is also possible that 'or' here means 'and' or even 'rather,' in which case both outcomes are combined. And Allah's bounty is even greater than that. End quote. In conclusion, a thousand good deeds are written for him, and a thousand sins are erased.