NET
20 You will be loyal to Jacob and extend your loyal love to Abraham, which you promised on oath to our ancestors in ancient times.
Darby
20 Thou wilt perform truth to Jacob, loving-kindness to Abraham, which thou hast sworn unto our fathers, from the days of old.
KJV
20 Thou wilt perform the truth to Jacob, [and] the mercy to Abraham, which thou hast sworn unto our fathers from the days of old.