Mishnah/Seder Nashim/Tractate Sotah/Chapter 3/2
He waved it and brought it near. A handful was then burnt, and the residue (remained) was eaten by the priest. He would make her drink and after this he offers up the meal offering. R. Simon says: offer up the meal offering after causing her drink, as it is said: “after he causes the woman to drink the water”. But if he made her drink after he had offered up the meal offering [it is still] valid.