וַיַּחְפְּר֥וּ עַבְדֵֽי־יִצְחָ֖ק בַּנָּ֑חַל וַיִּ֨מְצְאוּ־שָׁ֔ם בְּאֵ֖ר מַ֥יִם חַיִּֽים׃
I kopali też słudzy Ic'haka w dolinie, i znaleźli tam źródło wód żywych.
Radak on Genesis
ויחפרו, they dug even deeper than initially in order to supply sufficient water for the livestock.
Tur HaArokh
וימצאו שם באר מים חיים, “they found a well of spring water in that region.” The reason the Torah stresses the origin of this water is that the shepherds of the region had accused Yitzchok’s shepherds of diminishing their own water supply by letting their sheep drink from the water of the נחל, the local stream. The water found by Yitzchok’s shepherds did not originate in that stream, but represented a new and additional water supply. Yitzchok’s herds and flocks did not need to use the locally available sources of water.