I am weary with my groaning - I am exhausted or worn out with it. That is, his sorrows were so deep, and his groaning was so constant, that his strength failed. He became “faint” under the weight of his sorrows. All persons in trouble have experienced this effect - the sense of weariness or exhaustion from sorrow.
All the night make I my bed to swim - That is, he wept so much that his bed seemed to be immersed in tears. This is, of course, hyperbolical language, expressing in a strong and emphatic manner the depth of his sorrows.
I water my couch with my tears - The word here rendered “water” means to melt, to flow down; then, in the Hiphil, to cause to flow, to dissolve. The sense here is, that he caused his couch to “flow” or “overflow” with his tears. We would say, he “flooded” his bed with tears. This verse discloses the true source of the trials referred to in the psalm. It was some deep mental anguish - some source of grief - that exhausted his strength, and that laid him on a bed of languishing. No circumstances in the life of David better accord with this than the troubles which existed on account of the ungrateful and rebellious conduct of Absalom, and it is most natural to refer it to this. Many a parent since the time of David has experienced “all,” both mental and bodily, which is here described as a consequence of the ingratitude and evil conduct of his children. The tragedy of “Lear” turns entirely on this.