"...bless and do not curse" (NIV) Romans 12:14b.
Words carry power and influence that is why God attaches high importance to words (Psalm 138:2, Proverbs 30:6a, 1Thessalonians 5:24). For example, He instructed His priests in the past (Numbers 6:23) to generously speak the following words into the lives of His people:
"The LORD bless you and keep you; the LORD make His face shine on you and be gracious to you; the LORD turn His face towards you and give you peace." (Numbers 6:24-26)
These are words of benediction aimed at making a great impact on the lives of the people. Since we are God's holy priesthood today (1Peter 2:5), we must emulate that and do more. By speaking such words in people's lives, we are in effect making God's greatness, goodness and love known.
Words of benediction are life (John 6:63, Proverbs 18:21) and conversations full of grace and seasoned with salt are great blessings of peace and kindness (Colossians 4:6). Therefore, our words must make a difference in someone's life today; that may be the very thing they need to get going in life at the moment.
Bless with your words and not curse for it is also a sign of God's love working in you. Stay blessed.