[19]. Refers to a pagan custom before Islam where Arabs would alter the sacred months (e.g., delay or swap them) to make fighting permissible when it suited their interests. For example, if they wanted to wage war during a sacred month, they would declare it non-sacred and shift the sanctity to another month.
[20]. The second was his companion, Abu Bakr.
[21]. I.e., their claims and slogans of disbelief.
[22]. I.e., "Laa ilaaha illal laah" (there is no true deity except Allāh).