Muhammad bin Hatim Al-Samayn محمد بن حاتم البغدادي - السمين · The Book of Ghusl and Tayammum

"The Messenger of Allah (ﷺ) said: 'None of you should perform ghusl in standing water while he is Junub.'"

"You did the right thing." Then another man became Junub so he performed Tayammum and prayed. He came (to the Prophet (ﷺ)) who said to him what he had said to the other man- meaning, "You did the right thing."