"My dear Kṛṣṇa, in this way the problem will not be solved. I am becoming Your disciple. I am not talking anymore as friend." Śiṣyas te 'ham: "I become Your disciple." Because you cannot argue with guru. That is praṇipāta.
Therefore we must have a guru where exact knowledge is coming, without any mistake. Because we cannot argue. So we must find out such guru, where perfect knowledge is coming. Just like... Therefore guru is... Ācāryaṁ māṁ vijānīyāt. Guru must be perfect representative of Kṛṣṇa.