Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states: “When we speak of the proper attire for men, we must make a distinction between the absolute minimum that we are required to cover at all times for the validity of our salah, and the proper attire that we should wear while venturing out to the mosque or appearing in social gatherings or in public places.
The absolute minimum attire for the validity of salah in case of males is to cover the body from navel to knee (that is, covering the `awrah). Prayer is not considered valid without it unless a person has no choice because of circumstances beyond his control or means.
The fact that this is the minimum requirement for the validity of Prayer, however, does not mean that one is allowed to come out to the mosque wearing shorts or wearing anything less than the appropriate attire that is mandated by the specific standards of the society he is living in. For we are told in the Qur’an, “O Children of Adan! Wear your adornments at every place of worship [i.e., wear proper and decent attire], and eat and drink, but not excessively. For Allah loves not the excessive.” (Al-A`raf: 31).
The Shari`ah has left the definition of appropriate attire as undefined in order to allow for variations due to change of norms and customs in each society. Since Islam is a universal religion applicable for all times, we cannot impose the appropriate attire of one society on another so long as there is no breach of a fundamental principle of Shari’ah. For it is quite possible that the proper attire in a particular society may involve covering the whole body from head to toe including the head and shoulders, while in another society head gear may not form part of decent attire. It is for this reason that Imam Shatibi said that the issue of covering the head in Prayer for males is left to the norms and customs of a society, for it may be considered as part of a gentleman’s attire in one society, while it may not be the case in another. So, it would be recommended in the former case, while it is not so in case of the latter.
To be more explicit, an Englishman who is not in the habit of covering his head is not expected to do so while praying in his society, even though praying while uncovering the head may be undesirable in societies where covering the head is the norm and therefore considered as part of appropriate dress.
Coming specifically to the issue of covering the shoulders, we meet the Prophet’s words to the effect that one is not supposed to pray without covering the shoulders. This is not contradicted by other reports which suggest that the Companions often prayed covering only from the navel to the knees. For the first case is referring to better times when people had enough means to get themselves proper clothes, while the second is referring to the harsh, penurious conditions the early Muslims were living in. This is why we are told in another Hadith, “When Allah provides for you in abundance, you also treat yourself accordingly.” In the same spirit, the Prophet (peace and blessings be upon him) said, “Allah loves His servant to show signs of His favours on him (by appearing in public dressed appropriately).”
In conclusion, we are to dress appropriately while praying according to our circumstances and means. When one is praying alone at home, he is excused if he dresses only from the navel to the knee. But when going to mosque or appearing in social gatherings, we should dress appropriately according to the best standards of the society we are living in.”