Talmud do Amosa 9:6

When three people sit and engage in Torah together, the Holy Blessed One considers it as if they had become one unified troop before Him, as it says (Amos 9:6), “Who built His chambers in the heavens, and founded His troop on earth. (Who summons the water to the sea and spills it out on the face of the earth. the Eternal is His name.)” From this you learn that three who sit and engage in Torah are regarded as if they had become a unified troop before the Holy Blessed One.