The Hebrew verb saphach means to join, to attach, to add to, or to unite oneself with. Appearing about 20 times in the Old Testament, it describes the act of attaching or adding something or someone to a group, household, or people.
Saphach occurs in an important context in 1 Samuel 2:36 regarding the humiliated house of Eli: remnants will come begging to be attached to another priestly family. More theologically significant is Isaiah 14:1, which promises that 'aliens will join them and unite with the house of Jacob' — using saphach to describe Gentiles attaching themselves to Israel and to the people of God. This vision of inclusion anticipates the New Covenant expansion of God's family beyond ethnic Israel. The related noun saph (threshold) suggests the image of those who position themselves at the door, seeking entry. The verb captures the act of voluntary attachment — joining one's life and destiny to another's — which lies at the heart of covenantal theology. Ruth's famous declaration to Naomi, 'Your people will be my people,' exemplifies this saphach spirit even without using the exact word.