Why did the Prophet (peace be upon him) order the man who made a mistake in his prayer to repeat it, while he did not order the man who spoke in his prayer out of ignorance to repeat it?

The Prophet (peace be upon him) commanded the one who prayed poorly to repeat his prayer because he had omitted a pillar, whereas he did not command Mu'awiyah ibn al-Hakam al-Sulami to repeat his prayer, even though he had committed an invalidating act out of ignorance, as speaking was initially permissible.

This illustrates the difference between omitting a commanded act and committing a prohibited act. Ignorance is not an excuse for omitting pillars that necessitate repeating the prayer, unlike committing prohibited acts.

Al-Zarkashi mentioned that ignorance and forgetfulness are excuses for prohibited acts but not for commanded acts, citing the hadith of Mu'awiyah ibn al-Hakam and Ya'la ibn Umayyah as evidence.

The difference is that the purpose of commanded acts is to establish their benefits, while the purpose of prohibited acts is to deter from their harms. Ignorance or forgetfulness does not involve the intention to commit the prohibited act, so it is excused.