Ramban

CHASHAK’ (HE TOOK DELIGHT). The meaning thereof is that He had “bound” Himself with you with a mighty bond that He will never be separated from you, similar in expression to ‘vachashukeihem’ (and their fillets — silver threads encircling the pillars of the Tabernacle) shall be of silver. And He has chosen you from among all peoples that you be His treasure and inheritance, for “being chosen” always implies selection from others. And he stated the reason, But because the Eternal loved you He chose you, meaning, He saw you to be worthier than all peoples to be loved by Him and to be chosen for love. He mentioned for this no [other] reason except that you were chosen [because of His love for you], for he who is chosen to be loved, is known to be ready to suffer whatever comes upon him from his lover, and the Israelites are more qualified for that than any other people. As the Rabbis have said: “Three [creatures] are of strong character, Israel among the nations etc.,” for Israel has stood by Him in all trials. [When challenged by the nations, Israel has stubbornly declared,] “Either [we remain loyal] Jews or [we will be] nailed to the stake.” And the purport of the word you [and He chose ‘you’] is “because of your fathers,” who became so worthy that He swore to them in order that no sin should cause [His] promise [to them] to be nullified. Therefore He brought you out from the land of Egypt with a mighty hand. And He redeemed you — this is an allusion that He smote them in your stead, similar to what is said, I have given Egypt as thy ransom, Ethiopia and Seba for thee.