There are three distinct ideas: severe windows affecting previously-binding Fard/Wajib acts; newly-arising causes inside those windows that may still be performed with Karahah; and broader times in which Nafl is disliked. Keeping them separate prevents overstatements such as 'no prayer of any kind is ever valid at sunrise.'
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Do Not Use One Label for Every Restriction
Prohibited and Disliked Times of Prayer
There are three distinct ideas: severe windows affecting previously-binding Fard/Wajib acts; newly-arising causes inside those windows that may still be performed with Karahah; and broader times in which Nafl is disliked. Keeping them separate prevents overstatements such as 'no prayer of any kind is ever valid at sunrise.'