Saul went to sleep jealous; he woke up demon-possessed (1 Sm 18:10).
Cain also slept on his jealousy (Gn 4:5). He later committed the first homicide and fratricide.
The religious leaders of Jesus' time were jealous of Him. They refused to put their jealousy to death. Instead, they put God to death after brutally torturing Him (Mt 27:18).
The religious leaders after Jesus' time continue to crucify Jesus and hold Him up to contempt (Heb 6:6) by persecuting His followers (see Acts 9:5). They do this for the same reason that their forebears killed God — jealousy (see Acts 13:45).
Jealousy is very deadly. Jealousy was the motive for the first murder and the worst murder. In jealousy, we have killed both men and God. Jealousy is one of the oldest strongholds of the evil one (see 2 Cor 10:4), and it is stronger than ever today.
"Do you suppose it is to no purpose that Scripture says, 'The spirit He has implanted in us tends toward jealousy'? Yet He bestows a greater gift" (Jas 4:5-6). Therefore, by God's grace, "never act out of rivalry or conceit; rather, let all parties think humbly of others as superior to themselves, each of you looking to others' interests rather than to his own" (Phil 2:3-4).