Answered by Shaykh Amjad Rasheed
Is it wrong to rinse one’s mouth in wudu, and then one’s nose with new water?
There are many sunna ways of rinsing out one’s mouth and sniffing up one’s nose in wudu. Among them is what the questioner mentioned and that is called the method of fasl (separation) and it is not wrong. However, the best way is to use the method of jam` (joining ) and that is that one takes a handful of water and rinses one’s mouth with some of it and then sniffs it up one’s nose with the rest, and does this three times.
Amjad Rasheed
[Translated by Shazia Ahmad]