Answer:
(Fatwa: 1014/817=L/1430)
It is mustahab (desirable) to perform Tahiyyatul Masjid after entering mosque:
قال الحافظ في الفتح: واتفق أئمۃ الفتوی علی أن الأمر في ذلک للندب (إعلاء السنن 7:33)
Therefore, treating a mustahab act like wajib is not right on part of the Ghair Muqallideen.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
