How is the non-invalidation of fasting by janābah at dawn established here?

Four Modes of Textual Indication: ʿIbārah, Ishārah, Dalālah and Iqtiḍāʾ

• By removing the obligation of ghusl
• By making fasting a nighttime act
• From the implication of permissibility through the end of the night
• From divorce-related presupposition