اللَّهُمَّ افْتَحْ لِي أَبْوَابَ رَحْمَتِكَ
O Allah, open for me the doors of Your mercy.
Allahumma iftah li abwaba rahmatik
When to Read
This is the general dua for entering the masjid. While entering, one should also have the intention to guard their tongue from idle talk and gossip, understanding that the masjid is a place of worship and remembrance, not a place for backbiting. The intention to avoid such speech is paramount, even if a specific dua for it isn't recited upon entry.
How to Read
Recite this dua upon entering the masjid, preferably with the right foot first. Enter with humility and reverence, remembering you are entering the house of Allah. Keep your intention pure to worship Allah and avoid anything that displeases Him, including idle talk.
Virtues & Benefits
Entering the masjid with this dua invites Allah's mercy, which is the key to all good in this life and the hereafter. By intending to guard one's tongue, a Muslim honors the sanctity of the masjid and earns reward for refraining from sin. Gossip and idle talk are detrimental to individual character and community harmony, and avoiding them within the sacred space of the masjid is a sign of sincere faith.
Source & Authentication
Abu Usayd Malik bin Rabi'ah as-Sa'idi reported: I heard Allah's Messenger (ﷺ) say when he entered the mosque: Allahumma aftah li abwaba rahmatik. (O Allah, open for me the doors of Your mercy.) And when he went out of it, he invoked Allah (in these words): Allahumma inni as'aluka min fadlik (O Allah, I ask for Your bounty). Sahih Muslim 713