In this parable Jesus indicates his self-awareness of his unique , divine sonship. He was also tyring to teach that we tend to reject, and turn away from the message because we do not like the messenger.
The vineyard in today's context is the worldn into which the message is sent. The farmer(God )himself who sent his onle son to us and whom we rejected. Jesus is also trying to teach that the servants (the prophets of old) and by extension the disciples whob were chosen by Jesus himself to bear his message and us the followers(tenants) who are the religious leaders, who proclaim, share the word, and the church members, who hear/accept the word and is being called to live it.
However, the very ones who are sent to us to bring the word of God are rejected because we tend to look at the messenger rather than pay attention to the message. Hence, the scripture vers" the stones which the builders rejected shall become the head cornerstone." Jesus is trying to teach us that we must accept the message and not look at the messanger alone.