Moses recorded in the laws:

"Do not ... curse a ruler of your people." -- Exodus 22:28 (NKJV), Ecclesiastes 10:20

"Do not curse the deaf" -- Leviticus 19:14 (NKJV)

Job also said:

“If I have rejoiced at the destruction of him who hated me, or lifted myself up when evil found him

(Indeed I have not allowed my mouth to sin by asking for a curse on his soul)

-- Job 31:29-30

Jesus also confirmed this:

Bless those who curse you, pray for those who abuse you. -- Luke 6:28 (ESV)

Paul, a persecuted apostle, also wrote in his letter:

"Bless those who persecute you - bless and do not curse." -- Romans 12:14 (NKJV)