You shall bring the bull close, before the Tent of Meeting; and Aharon and his sons shall lay their hands on the head of the bull.
The possuk uses a singular expression וְסָּמַךְ, when it is referring to Aharon and his sons. Why?
The Ohr Hachaim quotes the Tosefta that says that when five people are bringing one Korban together, all of them have to lay their hands on it, one of them cannot do it.
This is why the Torah commands them to do it individually, each one has to lay their hands on the bull individually.
In Parshas Tzav, when the Torah describes what Aharon did, it says it again in a singular language.
The Ohr Hachaim explains the necessity of this repetition. If it would only have written it once, in this week’s Parsha, someone may think that only Aharon had to lay his hands on the bull. Aharon was to blame for the Golden Calf, and he needed his own forgiveness for it. That is why only he laid his hands on the bull.
In order to prevent a person from making this mistake, the Torah writes twice that this laying of the hands was done individually. This shows that each of the sons of Aharon had to lay their hands on the bull, and this teaches us that any Korban brought by multiple people needs each of them to lay their hands.
