Is reciting dua-e-qunooth in the witr salaat a wajib or is it just a sunnah? Can we recite any other dua in place of dua-e-qunooth? (2) A person was praying salaat and was towards the end of it but did not end the prayers by saying “AS SALAMU ALAIKUM WA RAHMATULLAH” but instead he completed the qaaidah-e-aakhira and got up and got engaged in other daily activities (he forgot to end the prayers by saying “AS SALAMU ALAIKUM WA RAHMATULLAH”) is his salaat valid in this case?