Recitation During Salah (Whispering Or Reciting In Heart)
It should be like a whispering as God says: وَلَا تَجْهَرْ بِصَلَاتِكَ وَلَا تُخَافِتْ بِهَا وَابْتَغِ بَيْنَ ذَٰلِكَ سَبِيلًا do not offer that prayer of yours very loudly nor in a very low tone. In fact, adopt a middle way between the two. (17:110)