Which preposition to use with gurus

for Occurrences 1%

Although I went ploughing with Guru for several days in a row, he never let me plough on my own because getting the right balance was still very difficult for me and if any of the bullocks got hurt due to my inexperience he would have to give the animal at least 15 days' rest which would cost him heavily in earnings.

of Occurrences 1%

They were near the end of their journey when the bear-man asked suddenly: "Manjhi, have we not passed Serampore?" "Are you the guru of boatmen that you question me?" replied the manjhi, and then, in a more conciliatory tone, added: "We are going higher up for a crossing.

Which preposition to use with  gurus