Entering the Masjid and Leaving it

Here is a blog post by IslamicSalvation, which can be found here:

باب القول عند دخول المسجد و الخروج منه‏

Chapter on what to say when entering the Masjid and exiting from it

علي بن إبراهيم،  عن أبيه، عن عبدالله بن المغيرة، عن عبدالله بن سنان، عن أبي عبدالله (عليه السلام) قال: إذ دخلت المسجد فصل على النبي (صلى الله عليه وآله) وإذا خرجت فافعل ذلك – حسن

Ali bin Ibrahim from his father (Ibrahim bin Hashim) from Abdallah bin Mughira from Abdillah bin Sinan from Abi Abdillah (a.s) who said : when you enter the Masjid then send Salawat (pray for peace and blessings upon him) on the prophet and if you leave the Masjid do so again.
(Hasan due to Ibrahim bin Hashim)

علي بن إبراهيم،  عن أبيه، عن الحسين بن سعيد، عن فضالة، عن أبان، ومعاوية بن وهب قالا: قال أبوعبدالله (عليه السلام): إذا قمت إلى الصلاة فقل: "اللَّهُمَّ إِنِّي أُقَدِّمُ إِلَيْكَ مُحَمَّداً ص بَيْنَ يَدَيْ حَاجَتِي وَ أَتَوَجَّهُ بِهِ إِلَيْكَ فَاجْعَلْنِي بِهِ وَجِيهاً عِنْدَكَ فِي الدُّنْيَا وَ الْآخِرَةِ وَ مِنَ الْمُقَرَّبِينَ اجْعَلْ صَلَاتِي بِهِ مَقْبُولَةً وَ ذَنْبِي بِهِ مَغْفُوراً وَ دُعَائِي بِهِ مُسْتَجَاباً إِنَّكَ أَنْتَ الْغَفُورُ الرَّحِيمُ " – حسن

Ali bin Ibrahim from his father (Ibrahim bin Hashim) from Husayn bin Said from Fadhala (bin Ayub) from Aban (bin Uthman) AND Muawiya bin Wahb who said : Abu Abdillah (a.s) said : When you stand to (go and) pray then say : O my Lord, I  give preference to Muhammad (s.a.w.w) (over myself in front of you) and place Him between my hands in need (of you), and turn to you by him, so make me by him an intimate of yours in this world and the next, and from among the close ones (to you), and make my prayers by him accepted, and my sins by him forgiven, and my supplications by him answered, Indeed you are the most Forgiving the Merciful.
(Hasan due to Ibrahim bin Hashim)