The Vedanta Sutras of Badarayana, Commentary by Sankara (SBE38), tr. by George Thibaut  at sacred-texts.com
45. (They are) the work of the priest, this is the view of Audulomi; since for that (i.e. the entire sacrificial work) he is feed.
The assertion that the meditations on subordinate members of the sacrifice are the work of the sacrificer is unfounded. They rather are the work of the priest, as the teacher Audulomi thinks. For the priest is rewarded for the work together with its subordinate members; and the meditations on the udgîtha and so on fall within the performance of the work since they belong to the sphere of that to which the person entitled (viz. the lord of the sacrifice) is entitled. Hence they are to be carried out by the priests only, the case being analogous to that of the restrictive rule as to the work to be performed by means of the godohana vessel. In agreement herewith scripture declares the udgâtri to be the agent in knowledge, in the following passage, 'Him Vaka Dâlbhya knew. He was the udgâtri of the Naimishîya-sacrificers' (Kh. Up. I. 2, 13). With reference to the circumstance noted by the pûrvapakshin that scripture states the fruit to belong to the agent, we remark that this makes no difference: For with the exception of cases expressly stated the priest cannot be connected with the sacrifice since he subserves the purposes (acts for) another (viz. the lord of the sacrifice).