One of the hardest things we have to do is wait for something to happen, especially if it is something we are looking forward to and it seems to be delayed. The Bible word "to wait" is related to the word for "hope." Even the word hope, in many of our modern languages, has an element of uncertainty. If I say "I hope so," you will understand that the thing may happen but it might not.
When I was in training in the military, we were taught how to behave if we were taken prisoner and put in a prisoner of war camp. Our group of trainees was taken from a closed room where we had spent many hours. We were taken to the prison camp with bags over our heads. When we arrived it was dark. No one had a watch, and no one had any idea what time it was. This was in the winter time, when it got dark very early.
All through the night we were put through different training activities outside in the dark. Hour after long hour. And it just stayed dark. We were not allowed to sleep, which would have helped the time pass faster. It seemed like the longest night I had ever known. And yet no one in that camp thought that morning would never come. We had an absolute certainty that the sky would eventually begin to get lighter and the sun would dawn.
The writer of (Psalm 130) describes waiting for the Lord in a similar way. With the same absolute certainty that the night watchmen on the city walls know that morning will come, so God's people wait for the Lord with the assurance that he will hear our cry, he will come to help us. It may seem long, but he absolutely will come.