What is the ruling on praying in a undershirt: a men's sleeveless undershirt?

If the garment does not cover both shoulders or one of them, the prayer performed with it is considered valid according to the majority of scholars, and this is the most preponderant opinion. It is, however, recommended for the worshiper to come to prayer in the best possible appearance and most beautiful clothing, based on the Almighty's saying: "O Children of Adam, take your adornment at every place of prayer."