Saul was jealous of David because David did greater things than Saul had done and became more popular than Saul was (see 1 Sm 18:7). Because of this jealousy, Saul repeatedly tried to kill David (1 Sm 19:1).
Jesus did greater things than the religious leaders of His time. He was so popular that great multitudes "kept pushing toward Him to touch Him" (Mk 3:10). The religious leaders became jealous of Jesus and handed Him over to be crucified by the Romans (Mt 27:18).
The early Church did even greater things than Jesus had done (Jn 14:12). Because of this, the enemies of the Church "became very jealous" (see Acts 13:45) and persecuted the Church, even to the point of killing many Christians.
Even today, the Church is sometimes so united with the Lord that it does His wondrous works and thereby becomes the object of jealousy, persecution, and martyrdom. In this year of the Great Jubilee, may the Church show the world something to be jealous of.
May the world resist the temptation to jealousy. May it yield to Jesus and join the Church. But if the world falls into the sin of jealousy, may the Church be worthy of being persecuted and martyred (see Acts 5:41).