Genesis 21:20

And the Word of the Lord was the helper of the youth, and he grew and dwelt in the wilderness, and became a skilful master of the bow.

ROVEH KASHOTH (AN ARCHER). Since kashoth is an adjective, they is an adjective, or more precisely, a shem hatoar, (a noun-adjective), as is also roveh, how could two adjectives appear without a noun? Therefore they said that the two words, roveh kashoth, are not in construct with one another, but they are interpreted as roveh vekashoth (a shooter of arrows and maker of bows) with the companion noun of each adjective being tacitly understood. Ramban’s opinion, however, is that since roveh may mean either “a shooter of arrows” or “a thrower of stones,” the word kashoth is used in order to explain that he was a shooter with the bow, meaning, a shooter of arrows and not a thrower of stones. have said that roveh is one who shoots arrows, the word being derived from the expressions: His archers compass me round about; The archers have dealt bitterly with him, — and kashoth is one who makes arrows.
A more correct interpretation is that roveh is a shooter, and it can refer to one who shoots arrows or throws stones or other objects, even as it is said, Behold this heap… which I have thrown up between me and thee., 31:51. Therefore, the verse describes him further by saying that he was a shooter with the bow. In a similar sense is the verse, And the shooters of arrows by the bow overtook him.

רובה קשת. Pulling the string of a bow. We are dealing with two successive forms of an activity, as in Genesis 49,23 וימררוהו ורבו, “they shot at him and harried him.” [I am choosing this translation of the JPS seeing that in both verse 23 and 24 where the “bow” and the “arrows” are mentioned. Ed.] The expressionרובה as a variation of רבב is found in Job 16,13 as it is in Psalms 48,13, where it is derived from the root סבב. A construction שומו as a derivative of שמם is found in Jeremiah 2,12, just as the construction דומו derived from דמם is found in Isaiah 23,2. Also, the expression דממה דקה, a very low voice, in Kings I 19,12 is a similar construction. The common feature in all these constructions is that the last root letter appears twice in succession. Our example of רובה is different, seeing that there is no such repetition of the last root letter. Therefore its root is רבה, and the construction is similar to עושה from עשה, or בונה from בנה, or קונה from קנה.

ויהי אלוקים את הנער, He ensured Ishmael’s success in his undertakings.

ויגדל, he amassed wealth. We encounter a similar meaning of the word ויגדל in Genesis 26,13 describing Yitzchok’s economic success in the land of the Philistines.

וישב במדבר, first he settled in the desert nearby, moving further afield to the desert of Paran later on.

ויהי רובה קשת, the word רבה may be understood as נער, lad. Onkelos translates it as רביא. The word קשת is an adjective mode of the word keshet, bow. The mode is similar to that of ganav, someone practicing thievery, or salach, someone apt to forgive. An alternative way of understanding the word רובה is that it means the same as יורה, someone shooting. He developed the technique of shooting arrows by means of a bow. [a far less dangerous mode of hunting than bodily facing the adversary. At this point Kimchi draws on the points made already by Rash’bam on our verse. Ed.] He adds that the ability to hit distant targets enables archers to practice what the Torah called ידו בכל, attacking all and sundry, even distant targets. He quotes examples of ancient peoples who became known for this skill, apparently distant descendants of Ishmael, especially the בני קדר. Reference is made to these people, (in that capacity?) in Isaiah 21,17 Our sages suggest that it is appropriate for the sons to perfect themselves in the trade, vocation or skills in which their father excels. (Erchin 16) They also base this on Kings I 7,14 where Chirom is described as having mastered the art of being a coppersmith just like his father. Yaakov’s sons, when presented to Pharaoh in Genesis 47,3, also were described as continuing the tradition of their father as shepherds.

רובה קשת, “an archer.” He was hunting by shooting arrows at his prospective victims. The word רובה is used here in the same sense as Genesis 49,23, where Yaakov uses it in his blessing for Joseph, i.e. ורובו, implying that his brothers, or Potiphar and his wife, had hunted him. Some commentators understand the word as a Hebrew alternative for the Aramaic word: רביא, translation of Isaiah 9,5: כי ילד יולד, “for a child has been born;” We find in the Talmud, tractate Chulin folio 20, the expression: יקבלו הרובים את תשובתן, “let the children (of Rabbi Chiyah) receive their reply.”