What is the ruling on someone whose house is next to the mosque but does not pray in it, what are the conditions for the acceptance of supplication, and what are the best supplications for the deceased?

The best supplications are those found in the Quran and Sunnah (definition), including: Alhamdulillah (all praise is due to Allah), asking for pardon and well-being, and the Sayyid al-Istighfar (master of seeking forgiveness). In the Hadith (definition): "The best remembrance is 'La ilaha illallah' (there is no god but Allah), and the best supplication is 'Alhamdulillah' (all praise is due to Allah)." And in another Hadith: "There is no supplication a servant can make better than: 'O Allah, I ask You for well-being in this world and the Hereafter.'" And "Ask Allah for pardon and well-being in this world and the Hereafter, for if you are granted pardon and well-being in this world and the Hereafter, you have indeed succeeded." And Sayyid al-Istighfar is: "O Allah, You are my Lord, there is no god but You. You created me, and I am Your servant, and I am abiding by Your covenant and Your promise as much as I can. I seek refuge in You from the evil of what I have done. I acknowledge Your blessing upon me, and I acknowledge my sin, so forgive me, for indeed, none can forgive sins except You."