What is the ruling when a husband says to his wife, 'You are divorced according to the Sunnah,' and the divorce timing aligns with the Sunnah?

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If the husband states, 'You are divorced according to the Sunnah' (Anti Taliqun lis-Sunnah), and the timing of the pronouncement is indeed within the prescribed time frame of the Sunnah (for divorce), the divorce takes effect immediately due to the existence of the stipulated condition.