Rashi on Leviticus 12:8/רש"י על ויקרא י״ב:ח׳

1אחד לעלה ואחד לחטאת THE ONE FOR A BURNT-OFFERING AND THE OTHER FOR A SIN-OFFERING — Scripture puts it (the עולה) first only by way of mention, but so far as offering it is concerned the sin-offering precedes the burnt-offering; thus do we learn in the Treatise Zevachim 90a, in the chapter commencing כל התדיר .