Rashi on Genesis 21:16/רש"י על בראשית כ״א:ט״ז

1מנגד means some distance away.

2כמטחוי קשת AS IT WERE A BOWSHOT — about two bowshots (since the first word is really plural) (Genesis Rabbah 53:13). The word signifies shooting an arrow — we find it so used in the Mishna (Sanhedrin 46a). If you say that it should have been written כמטחי קשת (since the root is טחה) then I say that it is quite regular for a ו to be inserted in these forms as (Song 2:14) “in the clefts (בחגוי) of the rock”, where בחגוי is of the same derivation as חגא in (Isaiah 19:17) “And the land of Judah shall become a breach (לחגא) to Egypt” and of the same derivation as יחוגו in (Psalms 107:27) “They reeled (וחוגו) to and fro and staggered like a drunken man”. Similar, also, is (Psalms 65:6) “The ends of (קצוי) the earth” which is of the same derivation as ,קצה, end.

3ותשב מנגד SHE SAT AT A DISTANCE — (this is the second time that it is so said) — now that he came nearer to death she moved further away from him.