Surely blessing I will bless thee (εἰ μήν εὐλογῶν εὐλογήσω σε).
Ει μήν as a formula of swearing N.T.o. In lxx, see Num 14:23, Num 14:28, Num 14:35; Isa 45:23; Eze 33:27; Eze 34:8. Blessing I will bless is a Hebraism, emphasizing the idea contained in the verb. Comp. lxx, Gen 22:17; Num 25:10; Deu 15:4.