Albert Barnes Commentary Song Of Solomon 5:4

"My beloved put in his hand by the hole [of the door], And my heart was moved for him." — Song Of Solomon 5:4 (ASV)

Put in his hand - Through the opening for the lock (literally, "from" the opening), in order to raise the pins that fastened the bolt. The ancient Near Eastern lock is a hollow piece of wood attached to the doorpost, into which a sliding bolt is inserted. As soon as the bolt has been pushed fully in, a number of pins drop into holes prepared for them. To raise these pins, and so enable the bolt to be withdrawn, is to unfasten the lock.

This is commonly done with a key (literally, an "opener"), but can often be accomplished with the fingers if they are dipped in paste or some other adhesive substance. For this purpose, the beloved here inserts his fingers, anointed with costly ointment, which will soon drip onto the bride's fingers when she rises to open for him.