علَيكُم بِإتيانِ المَساجِدِ؛ فإنّها بُيوتُ اللَّهِ في الأرضِ ، ومَن أتاها مُتَطَهِّراً طَهَّرَهُ اللَّهُ مِن ذُنوبِهِ وكُتِبَ مِن زُوّارِهِ فَأكثِرُوا فيها مِن الصَّلاةِ والدُّعاءِ.

It is incumbent upon you to attend the mosques, for verily they are the houses of Allah on earth. And whoever enters them having purified himself, Allah will purify him of his sins and will record him down as one of its frequenters, so perform many prayers and supplications therein.

Amali al-Saduq, p. 293, no. 8