Wiktionary
post haste
adv. (alternative spelling of posthaste English)
Usage examples of "post haste".
And he requires your haste-post haste appearance Even on the instant.
The King, who was now in a hurry to marry Anne Boleyn, thought this such a good idea, that he sent for Cranmer, post haste, and said to LORD ROCHFORT, Anne Boleyn’.
Yabu had come from Yedo, Toranaga's capital city, more than a hundred miles away, post haste, furtively and at great personal risk, and it was vital that he return as quickly.