Old English hǣs; related to hātan to promise, command
Word Origin and History for hest
n.
"bidding, command," Old English hæs "bidding, behest, command," from Proto-Germanic *hait-ti-, from *haitan "to call, name" (see hight (v.)). With -t added in Middle English on model of other pairings (cf. wist/wesan).