John Gill Commentary Mark 4:9

"And he said, Who hath ears to hear, let him hear." — Mark 4:9 (ASV)

And he said to them To the multitude of hearers that were on the sea shore attending to the word preached, and among whom, doubtless, there were all those sorts of hearers mentioned in this parable:

he that has ears to hear, let him hear : observe, and take notice of what has been said, as being of the greatest moment and importance: for a larger explanation and illustration of this parable, see the notes on (Matthew 13:3–9) .