Leviticus 16:12-13

He shall take a censer full of burning coals from the [bronze] altar before the LORD, and two handfuls of finely ground sweet incense, and bring it inside the veil [into the Most Holy Place], and put the incense on the fire [in the censer] before the LORD, so that the cloud of the incense may cover the mercy seat that is on [the ark of] the Testimony, otherwise he will die.