Why is Iblis stoned with seven small pebbles, while the fornicatress is stoned with large, unspecified numbers of stones?

One must submit to God’s rulings and laws, whether the wisdom behind them is known or not, for God knows best what benefits His servants. Ibn Baz was asked about the wisdom behind the ritual of throwing the pebbles (rami al-jamarat) and staying overnight in Mina. He replied that obedience to the Messenger of Allah, peace and blessings be upon him, is obligatory, and that everything legislated by Allah has wisdom behind it. Throwing the pebbles is a humiliation for Satan and an act of obedience to Allah, and staying overnight in Mina is to facilitate and ease the throwing of the pebbles.

There is a great difference between throwing the pebbles (rami al-jamarat) and the punishment of stoning (rajm). Stoning is a punishment for the married fornicator using large, egg-sized stones to inflict pain and death. It is a form of severe punishment and retribution, and it cannot be replaced.

As for throwing the pebbles, it is a ritual of Hajj performed with small pebbles. Its wisdom lies in following the example of the Prophet, peace and blessings be upon him, enraging Satan, emulating Abraham, peace be upon him, and establishing the remembrance of Allah. There is no connection between the stoning of the fornicator and the throwing of the pebbles; there is no basis for comparison.