Another interpretation: "to the house of Jacob"—by the merit of Jacob; "and tell the children of Israel"—by the merit of Israel.
Speaking to Jacob and Israel by the Merit of the Fathers
Yalkut Shimoni on Torah 276:3
דָּבָר אַחֵר לְבֵית יַעֲקֹב, בִּזְכוּת יַעֲקֹב, וְתַגֵּיד לִבְנֵי יִשְׂרָאֵל, בִּזְכוּת יִשְׂרָאֵל.