Last Sajdah of Imam Hussain (a.s)

Assalam alaykum.Some zaakirs recite that Imam Hussain a.s was beheaded (Allah’s curse be upon his killers) while doing sajdah of namaze khauf (for asr salaat) while some say he (a.s) was in sajda e shukr.My question is;(1)which of …