תְּשַׁלַּ֣ח קְצִירֶ֣הָ עַד־יָ֑ם וְאֶל־נָ֝הָ֗ר יֽוֹנְקוֹתֶֽיהָ׃
它的枝條伸展到大海，它的嫩枝延伸到大河。
Rashi
and it will produce a branch Heb. קציר. This is a branch, as (Ps. 80:12), “She sent out her boughs (קצירה) to the sea.”
Rashi
When its branches dry out The branches of its roots. Comp. (Ps. 80:12) “It sent forth its branches (קְצִירֶיהָ).” Also (Job 14:9): “And produce branches (קָצִיר).” I.e., when the little merit that Edom has for honoring his father, is depleted, then its branches shall be broken.