Resurrection of the dead תחיית המתים
Belief in the future revival of the dead — one of the Rambam's thirteen principles of faith.
The Torah says almost nothing explicit about resurrection, and the Talmud searches for hints in verses, since the Mishna declares that whoever denies it forfeits a share in the world to come. The strongest image is Yechezkel's: a valley of dry bones that grow sinew and stand, explained as «the whole house of Israel».
The Sadducees rejected it, and this became one of the fault lines with the Pharisees. The Rambam included it among the thirteen principles yet insisted that the highest state is the world of souls; his position was thought ambiguous, and he wrote a separate letter to explain.
In daily life the belief is constantly present: the second blessing of the Amidah is «who revives the dead», said three times a day, and burial customs follow directly from it.