Where does “ēs” come from?

ēs (Old Frisian) comes from Proto-Germanic ēsą, from Proto-Indo-European h₁ēdsto- — eaten.

Ancestry of “ēs”, step by step

Step	Language	Word	Meaning
1	Proto-Germanic	ēsą	food, carrion; prey; bait
2	Proto-Indo-European	h₁ēdsto-	eaten

ēs — Etymology, Origin & Word History | Etymology Explorer