Which preposition to use with yussuf

at Occurrences 1%

But first you had to get by Yussuf at the door.

for Occurrences 1%

The only money that ever changed hands in that connection was when the tax-gatherer came down on Yussuf for an extra levy, because of the added trade that conceivably might be expected to accrue through the advertisement obtained by serving such an exalted customer.

Which preposition to use with  yussuf