Tanveer Ahmed, a Sunni Muslim, had stabbed AsadShah outside his store in the Shawlands area of Scotland in March for "disrespecting" Islam.
The 40-year-old victim, who belonged to the Ahmadiyya sect and had been granted asylum in the UK after he fled persecution in Pakistan, later died in hospital.
Now Ahmed is reportedly encouraging others to do the same in his extremist messages, some of which appear to have been recorded and released after he was jailed for life in early August.
"I have the honour of sending him to the hell forever," he says in Urdu, according to 'The Independent' newspaper.
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Ahmed goes on to call Ahmadi Muslims "frauds" for their beliefs and accuses them of "contaminating the faithful".
"Whoever and wherever is listening my voice must make a resolve to protect the finality of prophethood. We will save the Lord's followers from going down to the hell - will protect their faith," he says.
The message then calls on listeners to repeat a chant vowing to "offer their lives and souls", ending with "There's only one punishment for insulters: cut off their heads, cut off their heads, cut off their heads."
They are believed to have been recorded on a mobile phone, possibly during a call made by Ahmed from Barlinnie Prison in Glasgow, Scotland.
At the time of his sentencing last month, Chief Superintendent Brian McInulty, of Police Scotland, described the attack as "utterly unacceptable and cannot be justified."
"Glasgow is a strong, united, multi-faith community that has immense pride in its diversity. Religious intolerance in any form is simply not tolerated in our society and Police Scotland will work in partnership with our communities to eradicate such behaviour," he said.
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