Genesis 37:21Meaning & Commentary from the Church Fathers

Those who orchestrated the Lord's crucifixion achieved their aims, yet Joseph's brothers, despite having their own plans, did not act upon them. The vision had to encapsulate less of the complete truth in order to undergo transformation, as otherwise it would fail to serve as a representation of what is to come. Thus, what is future was only depicted as a shadow. When they agreed to commit murder, their motives were already established in wrongdoing; it is noted that ‘Reuben heard this,’ and he intervened, saying, ‘We will not kill him.’

As they were preparing to take his life, Reuben intervened; instead, they threw him into a pit, disregarding Reuben's advice. (See Gen. 37:26)

Reuben, the firstborn of Jacob, intervened and urged his brothers, “Let us not take his life with our own hands! Instead, let him be cast into one of these pits, but do not harm him!” Reuben, with a compassionate heart, intended to rescue his beloved brother and return him safely to their father.