Commentary for I Samuel 2:11

Served Adonoy in the presence of Eili the kohein. From here [our Sages conclude] that "whoever serves before a Torah scholar is considered as though he had served before the Divine Presence."⁸Talmud Yerushalmi Eruvin 5:1. The reason being that a Torah scholar cleaves to ‘ה in his thoughts at all times so that even his physical activities are holy.

In the presence of: Meaning to say, in front of him. For he was teaching him how to serve the Lord.

Upon (al) his house: It is like, to (el) his house. Likewise (I Samuel 1:10), "So she prayed upon (al) the Lord," is like, to the Lord.

In the presence of Eli: It is like, in front of him - meaning to say that Eli was teaching him the service of God. And Yonatan translated it [in the Targum] as, "during the life of Eli the priest," just like Onkelos translated (Deuteronomy 7:10), "in his presence, to destroy him," as, "during their lives, to destroy them."