to give up or fail while others continue; to be forgotten or neglected
—All of his plans for making money fell by the wayside when he found out that he had cancer.

It was common for Jesus to teach using parables, such as this one:

Listen! A sower went out to sow. And as he sowed, some seeds fell along the path [fell by the way side], and the birds came and devoured them. Other seeds fell on rocky ground where they did not have much soil. They sprang up quickly because the soil was not deep. But when the sun came up, they were scorched, and because they did not have sufficient root, they withered. Other seeds fell among the thorns, and they grew up and choked them. But other seeds fell on good soil and produced grain, some a hundred times as much, some sixty, and some thirty. The one who has ears had better listen! (Matthew 13:3-9)

Here wayside means “the side of the road or path.” Jesus explained that this hard soil along the pathway represents those with hard hearts who do not understand his message. The rocky soil is those who receive the message but stop believing when troubles come. The thorny soil is those whose belief is choked out by the worries of life and the deceitfulness of wealth. And finally, the good soil is those who hear, understand, and believe.