Huzoor Tajush Shariah مد ظله العالي was asked if Namaz is valid while wearing a T-shirt or a Tie.
“La Ilaha Illa Allah, the Tie is a replica of the Cross, it is in the shape of the Cross, to wear it is impermissible and Haram. Rather, Ma’aazAllah (I seek Allah’s refuge), wearing it while knowing that this is a symbol of Christians and Christianity is a severe matter and it is to lose one’s Imaan. People are not allowed to wear Shirt and Pants as this is not the clothing of the pious and righteous people, and in the Qur’an we have been given the command:
خُذُوا زِينَتَكُمْ عِندَ كُلِّ مَسْجِدٍ
‘(O People), at the time of every Namaz wear that clothing which is a means of beautification for you and is specifically your own clothing.'”