Strong G1587 ἐκλείπω ekleipō · to fail

Luke

1. Luke 16:9
   And I say unto you, Make to yourselves friends of the mammon of unrighteousness; that, when ye fail, they may receive you into everlasting habitations.
2. Luke 22:32
   But I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren.