Sher Shah Sur was a Pashto speaker

Sher Shah Sur was a Pashto speaker. Pashtuns in 15th century India were settled as tribes so they were able to maintain Pashto for many generations. 

To encourage the preservation of mother tongue, Sher Shah gave higher salary to those soldiers who could speak it fluently.

Reference: Tarikh-SherShahi, English translation by H.M.Elliot, p-135

An imaginative portrait of Sher Shah