Albert Barnes Commentary 2 Kings 4:27

"And when she came to the man of God to the hill, she caught hold of his feet. And Gehazi came near to thrust her away; but the man of God said, Let her alone: for her soul is vexed within her; and Jehovah hath hid it from me, and hath not told me." — 2 Kings 4:27 (ASV)

She caught him by the feet - To take hold of the knees or feet has always been considered in the East to add force to supplication, and is a practice that continues even today. Compare Matthew 18:29; John 11:32.