The first occurrence
Behold now, your servant has found grace in your sight, and you have magnified your mercy, which you have shown unto me in saving my life; and I cannot escape to the mountain, lest some evil take me, and I die. Gen 19:19
The primitive root
chet ח = the wall, thus outside, divide, half
sin ס = thorn, thus grab, hate, protect
dalet ד = door, thus enter, move, hang
The story: The wall (chet) of protection (sin) behind which one allows others to shelter when the door (dalet) is opened.