7:8 I am going to apply a plumb line to My people Yisrael
Amos is shown a vision of a plumb line, a construction tool used to measure the vertical straightness of a wall by means of a string with a piece of lead tied to it. This is important, because if the wall is leaning or uneven, it will be unstable and may eventually collapse under its own weight as it is being built, or afterwards. Here, the plumb line is a symbol of God’s examination of the people’s moral uprightness. Their pretensions of integrity are symbolized by a wall being built higher and higher. When He checks it, he finds the measurements lacking.