It doesn’t say He was in the tomb for three nights.
It’s always three days. When Jesus talks abobut the temple being torn down and the masive bricks will not have one left on top of another, I will rebuild it in three days. Not three days and three nights.
For as Jonah was three days and three nights in the belly of the great fish, so will the Son of Man be three days and three nights in the heart of the earth. (Matt. 12:40)