He asks about someone who prays at home in home clothes, like casual wear or an undershirt as he says, what is the ruling on that?

We say that Allah the Mighty and Majestic says in His great Book: O children of Adam, take your adornment at every mosque, and eat and drink but do not be excessive. We say that it is recommended for him to take his adornment at every mosque, and adornment here is general.

In every garment a person wears, anything a person uses to adorn himself among people.

And even though the address and the reason for the verse is that it was revealed about the disbelievers of Quraysh, that they used to circumambulate the House naked.

So Allah the Mighty and Majestic commanded them to take their adornment, meaning their clothing, but when Allah mentioned adornment specifically,

He intended something greater than that, which is to cover their private parts.

Not just by simply covering, because a person can cover his awrah with leaves from the ground, and he can cover it with.

with anything that is not beautiful, so we say: what is meant is what is beautiful and suitable for the mosques.

The sunnah in this is to wear, to wear good clothes.

And what is considered good is what people usually adorn themselves with.

So, can a person pray in something less than that, just as an exception at home or the like? We say: doing it as an exception is different from making it a habit. Some people are used to coming in their clothes from outside the mosque or, for example, praying in their regular clothes.

in worn-out clothes and they get used to this, we say this is not honoring the symbols of Allah.

But as an exception, not as a habit, there is nothing wrong with that. It was narrated from Jabir ibn Abdullah that he prayed wearing only an izar without a cloak, and he said: I prayed with the Messenger of Allah ﷺ, meaning that he did not object to it.

And we say regarding this, that it is as an exception, not as a regular practice.

As for making it a habit, a person should not do so except by adorning himself, even if he prays at home. He should wear his shirt, prepare himself, and then perform the prayer. And Allah knows best.