'Bitter' in the Bible

Be alert so there is no man, woman, family, or a tribe whose heart is turning away from the LORD your God to go and serve the gods of those nations. Be alert so there will be no root among you that produces poisonous and bitter fruit,

Instead, their vine is from the vines of Sodom and the vineyards of Gomorrah. Their grapes are poisonous, their clusters bitter.