How many times should one rinse the mouth and sniff water after washing the entire body: is it once or three times?

Ghusl has two forms: a perfect form and a sufficient form.

The perfect form consists of ten things: intention (niyyah), saying "Bismillah," washing the hands three times, washing away any impurity from the body, performing wudu' (ablution), pouring water over the head three times to saturate the roots of the hair, pouring water over the entire body starting with the right side, rubbing the body, moving from the bathing spot to wash the feet, and it is recommended to run water through the roots of the hair and beard before pouring it over.

The sufficient form involves washing the entire body with water once, along with rinsing the mouth (madmadah) and sniffing water into the nose (istishaaq), and having the intention for ghusl and wudu'. This is sufficient, even though the first form is preferable and more complete.

Based on this, rinsing the mouth and sniffing water into the nose once is sufficient.