What is the status of the worker's discharge and wage entitlement if the work involves building a wall or digging a well on the hirer's property?

Primary text

If a man is hired to build a wall in the hirer's house or dig a well there, the worker is discharged from the work and deserves his wage immediately upon completion of his action. However, if the well is in the desert or the wall is in an undeveloped area, the worker is not discharged merely by completing the physical act. If the wall collapses after construction or the well caves in after digging but before delivery to the hirer, the worker is not discharged from the work. Ahmad, in the narration of Ibn Mansur, affirmed that if one is hired to use a thousand bricks in a specific structure, and he works but it collapses, he is still due the rent (wage).