If ye have faith as a grain of mustard seed, which, as he says ( Matthew 13:32 ), "is less than all seeds." He means a faith real and trustful, though it be small and weak. The phrase is proverbial, expressive of littleness and insignificance.

Faith as small as a mustard seed. ‘As small as a mustard seed’ was a common expression in Jesus’ day. It had become a proverbial saying used frequently by Rabbis to indicate the smallest amount. Jesus is telling his disciples they don’t need an abundance of faith, just a little bit of faith.

The mustard seed in Jesus’ example symbolizes the potential in faith. When a believer begins their journey, they have just begun to learn about how much God loves them, how much He wants to do for them, and all that He has for them.