Question:  What is the status of performing forty Salahs  in Masjidun Nabawi (Sallallahu Alahi Wasallam)?

Answer: it is Sunnah to perform 40 Salahs in Masjidun Nabawi. (Fatawa  Mahmudiyya  vol.3 pg.186) The Messenger (Sallallahu Alahi Wasallam) said:

مَنْ صَلَّى فِي مَسْجِدِي أَرْبَعِينَ صَلاةً لا يَفُوتُهُ صَلاةٌ كُتِبَتْ لَهُ بَرَاءَةٌ مِنْ النَّارِ ، وَنَجَاةٌ مِنْ الْعَذَابِ ، وَبَرِئَ مِنْ النِّفَاقِ

(احمد، والطبراني، جمع الفوائد)

 “Whoever performs 40 salawât consecutively in my Masjid will be exempted from the fire, its punishments and from hypocrisy.” (Jam’ul Fawâid)

And Allah Knows Best

Yusuf Moosagie