God, the Good Master, digs out a vat for tenants who will soon mock His messengers and murder His Son (Mk 12:1-8). The tenant farmers were entrusted to run the vineyard for the Master in His absence. They have been given much, and therefore much will be required of them (Lk 12:48). The Master has the right, in justice, to receive His own fruit from His own property, so He sent a messenger to receive His share of the fruit.
When the tenants beat the first messenger (Mk 12:3), the Master could have sent the police to evict the ungrateful tenants. Instead, He sent His prophets to enrich them, essentially to hoe around them another year (Lk 13:8). These were beaten, mocked, and even killed. Incredibly, the Master even sent His Son as a "last resort" (Mk 12:6). Doesn't the Master "get it"? Either the Master is incredibly naive or He is loving and merciful far beyond our ability to comprehend.
Jesus told the parable of the tenants for the religious leaders of His day (Mk 12:12). It was intended as a means to urge them to accept Him as God's Son. After being given so many chances to bear the fruit God sought, how did Jesus' hearers respond to Him? "They left Him and went off" (Mk 12:12).
Jesus seeks kingdom-fruit from us (Mk 12:2). We must repent deeply of the times we have heard Him and walked away (Mk 12:12). Let's be His disciples and bear much fruit (Jn 15:8).