It is like a mustard seed which, when it is sown on the ground, is smaller than all the seeds that are on the earth, Bible see other translations

“mustard seed.” For more information on this parable, see commentary on Matthew 13:32.

“when it is sown on the ground.” The farmer literally scatters the seed on the ground. It is not planted in the ground, but thrown on top of the soil, which is why the birds can come and eat it so easily.

Commentary for: Mark 4:31