Here are five biblical passages on joy:

“But the fruit of the Spirit is love, joy, peace,
forbearance, kindness, goodness, faithfulness” (Galatians 5:22).

“Though the fig tree does not bud and there are no grapes on
the vines, though the olive crop fails and the fields produce no food, though
there are no sheep in the pen and no cattle in the stalls, yet I will rejoice
in the LORD, I will be joyful in God my Savior” (Habakkuk 3:17-18).

“The LORD your God is with you, the Mighty Warrior who
saves. He will take great delight in you; in his love he will no longer rebuke
you, but will rejoice over you with singing” (Zephaniah 3:17).

“Restore to me the joy of your salvation and grant me a
willing spirit, to sustain me. Then I will teach transgressors your ways, so
that sinners will turn back to you” (Psalms 51:12-13).

“The seventy-two returned with joy and said, ‘Lord, even the
demons submit to us in your name.’ He replied, ‘I saw Satan fall like lightning
from heaven. I have given you authority to trample on snakes and scorpions and
to overcome all the power of the enemy; nothing will harm you. However, do not
rejoice that the spirits submit to you, but rejoice that your names are written
in heaven’” (Luke 10:17-20).

The cause of joy on earth and in heaven is our salvation.
Our joy is a cause in others’ salvation.