Question: Oh Virtuous Shaikh, May Allah facilitate for you [good], is doing things in an odd number for permissible things like drinking coffee and other than it or is it for things which have been reported in a text?
Answer: “Doing all things in an odd number is good. Cleansing oneself with dry items is done in an odd number. The Prophet (ﷺ) used stop cleaning himself with an odd number. He eats fresh dates in an odd number, like this. So all of the statements and actions are done in an odd number. Yes. Sunnah. This is from the sunnah. Yes. And with the vessels, if you drink, breath three breathes. This is an odd number. Do not breath two breathes only. Yes”.
[Taken from: https://www.ajurry.com/vb/showthread.php?t=37786 ]
Faisal ibn Abdul Qaadir ibn Hassan