‘And they saw him in the distance, and before he came near to them they conspired against him to kill him. And they said to one another, “See, the lord of dreams comes.” Come now therefore, let us kill him and throw him into one of the cisterns, and we will say, ‘An evil beast has devoured him', and we shall see what will become of his dreams.” '
Joseph's behaviour and attitude, and especially his dreams of superiority, have so filled his brothers with hatred that they decide to get rid of him once and for all. When they see him approaching, wearing his coat of many colours which emphasises his favoured position (it also showed he had not come to work), they felt bitter. There were a number of cisterns nearby, holes three metres or so deep widening underneath the surface, whose purpose was to catch and store rainwater for the dry season. Remains of such cisterns have been found near Dothan. They could easily hide a man's body. So they decided to murder him and throw him into a cistern. It would be easy to suggest he had met with an accident, for who would ever know?
“The lord of dreams.” A bitter statement that demonstrates their feelings. The dreams and their suggestions of lordship had clearly affected them deeply, as their final comment shows.