Wearing Short Sleeves In Ibadah

As a matter of ruling it is permissible for anyone to wear short sleeves or to have no shirt at all (whilst just covering the izar i.e. from above the navel to below the knee).

However to present oneself in front of Allah with short-sleeves is disrespectful and discouraged especially in Solat and when reading the Qur'an.

When one has the opportunity and means to wear better clothes, one should take the time to put them on. The Prophet Muhammad SAW's sleeves were up to the wrist and his clothes were loose and covered down approximately to half way between the knees and the ankles.