Jamieson, Fausset and Brown on Hebrews 11:31

31. Rahab showed her "faith" in her confession, Jos 2:9, 11, "I know that Jehovah hath given you the land; Jehovah your God, is God in heaven above, and in earth beneath."

the harlot--Her former life adds to the marvel of her repentance, faith, and preservation (Mt 21:31, 32).

believed not--Greek, "were disobedient," namely, to the will of God manifested by the miracles wrought in behalf of Israel (Jos 2:8-11).

received--in her house (Jos 2:1, 4, 6).

with peace--peaceably; so that they had nothing to fear in her house. Thus Paul, quoting the same examples (He 11:17, 31) for the power of faith, as James (Jas 2:21, 25; see on Jas 2:21; Jas 2:25) does for justification by works evidentially, shows that in maintaining justification by faith alone, he means not a dead faith, but "faith which worketh by love" (Ga 5:6).