SN41.8 Nigaṇṭha. Niganṭha Nātaputta. SN48.44 Pubbakoṭṭhaka. The Eastern Gatehouse. Discussion from Dhamma Wheel
http://dhammawheel.com/viewtopic.php?f=25&t=10185
These are two interesting Suttas about the role of saddha (faith).
A variation on the second is often told by Ajahn Chah’s students. I suspect that their retelling sometimes conflates both of these Suttas.