كتاب الطهارة
Read the English translation first, with the original Arabic directly underneath.
It was narrated that Abu Musa said:
"I came to the Messenger of Allah (ﷺ) when he was using the Siwak, and the end of the Siwak was on his toungue, and he was saying, "'A','a'."
عَأْعَأْ