Here is the concept of Indulgences in the Bible:
“Above all, love each other deeply, because love covers over a multitude of sins.” (1 Peter 4:8)
Our charitable works “cover over” the temporal punishments for our sins. And here are our temporal punishments in the Bible:
“Anyone who does wrong will be repaid for their wrongs, and there is no favoritism.” (Colossians 3:25)
And again:
“The servant who knows the master’s will and does not get ready or does not do what the master wants will be beaten with many blows. But the one who does not know and does things deserving punishment will be beaten with few blows." (Luke 12:47-48)
And you can look at the
Purgatory article at Scripture Catholic for more related scriptures. God bless.