All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
This Hadeeth was narrated in Saheeh Muslim and its wording is as follows: “Whoever performs ablution thoroughly and goes to the Friday (prayer) and attentively listens to the Khutbah, the sins he has committed between that Friday and the previous, in addition to three days will be forgiven for him. And whoever fiddles with pebbles has engaged in idle action.”
The Hadeeth was also narrated by other narrators in different wordings which are similar.
This Hadeeth means that whoever performs ablution thoroughly and perfectly and then walks to the mosque to perform the Friday prayer and when he enters the mosque he listens attentively to the Khutbah and does not distract himself with talking or fiddling with pebbles and the like, then Allaah The Almighty Will Forgive him for the sins that he committed between that Friday and the previous one. Al-Haafith Ibn Hajar said: "What is meant by the other one is the Friday that is before the present one. This was explained by Al-Layth from the narration of Ibn ‘Ajlaan that is reported by Ibn Khuzaiyymah and its wording runs as follows: 'His sins that he committed between this Friday and the previous will be forgiven.'"
This Hadeeth also indicates that three days will be added to the other seven days and therefore the sins of ten days will be forgiven. Al-Mubaarakfoori in Sharh At-Tirmithi said: "It seems that each reward of a good deed brings the reward of ten like it."
Concerning “And whoever fiddles with pebbles has engaged in idle action.” An-Nawawi prohibits fiddling with pebbles and the like during the Khutbah, and what is meant by idle action here is what is false, rejected and disliked.
Allaah Knows best.