The words "let boast" are understood from the previous phrase. Alternate translation: "but let the rich man boast of his low position" (See: [[rc://en/ta/man/translate/figs-ellipsis]])
A rich believer should be happy if God causes him to suffer. Alternate translation: "should be happy that God has given him difficulties" (See: [[rc://en/ta/man/translate/figs-ellipsis]])