שׁבע shb` niphal "swear (an oath)". Three times in Amos Adonai swears, declaring the solemnity of what follows:

• at 4:2 his oath affirms the certainty of the destruction to follow, and since he swears by "his holiness" also draws attention to the nation's failing
• at 6:8 Adonai swears by "himself" declaring that he hates "the pride of Jacob"
• but in 8:7 he swears by "the pride of Jacob" (presumably himself, since God cannot swear by anything or anyone less).

By contrast in 8:14 the people swear by their gods who will "fall".