It was narrated that Abu Hurairah said: "I heard the Messenger of Allah (ﷺ) say: 'Whoever comes to this mosque of mine, and only comes for a good purpose, such as to learn or to teach, his status is like that of one who fights in Jihad in the cause of Allah. Whoever comes for any other purpose, his status is that of a man who is keeping an eye on other people's property.'"
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا حَاتِمُ بْنُ إِسْمَاعِيلَ، عَنْ حُمَيْدِ بْنِ صَخْرٍ، عَنِ الْمَقْبُرِيِّ، عَنْ أَبِي هُرَيْرَةَ، قَالَ سَمِعْتُ رَسُولَ اللَّهِ ـ صلى الله عليه وسلم ـ يَقُولُ " مَنْ جَاءَ مَسْجِدِي هَذَا لَمْ يَأْتِهِ إِلاَّ لِخَيْرٍ يَتَعَلَّمُهُ أَوْ يُعَلِّمُهُ فَهُوَ بِمَنْزِلَةِ الْمُجَاهِدِ فِي سَبِيلِ اللَّهِ وَمَنْ جَاءَ لِغَيْرِ ذَلِكَ فَهُوَ بِمَنْزِلَةِ الرَّجُلِ يَنْظُرُ إِلَى مَتَاعِ غَيْرِهِ " .
sunnah.com