Makespeed, haste, staynot - Though these words appear to be addressed to the lad, yet they were spoken to David, indicating that his life was at stake, and only a prompt flight could save him.
Matthew Henry
Concise Bible Commentary
The separation of two such faithful friends was grievous to both, but David's case was the more deplorable, for David was leaving all his comforts, even those of God's sanctuary. Christians need not sorrow, as men without hope; but being one with Christ, they are one with each other, and will meet in his presence ere long, to part no more; to meet where all tears shall be wiped from their eyes.
SDA Bible Commentary (limited)
Volume 1-7
38. Make speed. Compare v.22. These words were added to impress upon David the extreme gravity of the situation.