Tosefta do Powtórzonego Prawa 16:17

And so too would Rabbi Eliezer say, even if one leg [of the priest] was on the pavement, [the service] is disqualified. One leg on the pavement and one leg on the bricks, [or] one leg on the pavement and one leg on a vessel (see Zev. 2:1): If the vessel was removed and he could stand on his own, [the service] is fit, and if not, it is disqualified. [If] he received [the blood] in his left and right hands at the same time, it is disqualified, [but] Rabbi Shimon renders it fit. [If] his left hand was supporting his right hand, all agree that it is fit. Rabbi Shimon would say, whenever [Scripture] says "hand," the right hand is required, and whenever it does not say "hand," the right hand is not required. [Similarly,] whenever it says "finger," the right finger is required, and whenever it does not say "finger," the right finger is not required. Rabbi Elazar bar Rabbi Shimon says, whenever it says "the gift of his hand" (e.g., Deut. 16:17), if he makes a modification in the gift [after it is designated], it is disqualified, [but if he makes a modification] in receiving it, it is fit. And whenever it says "receiving of the hand," if he makes a modification in receiving it, it is disqualified, but in giving it, is fit. [If] the priest received, the act of receiving is fit. [If] he received it in his right hand, [or] he received it in a consecrated vessel, the act of receiving is fit. [If] he went back and received, it is disqualified. [If] he received with his left hand, or with a profane vessel, it is disqualified. [If] he received the fit and sprinkled the disqualified, [or] he received the disqualified and sprinkled the disqualified, [the service is] disqualified.