Sheikh Mohamad Doar told a room of teenage girls in Sydney's west that they needed to stop being friends with non-believers in a lecture that also covered Islamic fashion and grooming.
'The reality is, my sisters, any friendship that is not built on the fear of Allah is only going to lead to hell fire so you need to be cautious.
'With your actions, you distance yourself from the corrupted people.'Sheikh Doar, from the Ahlus Sunnah Wal Jamaah Association, also told the forum, held at Punchbowl, that women would also be cursed by Allah if they plucked their eyebrows, waxed their body or shaved.
'You are not allowed the remove the hair of the eyebrow, it's a major sin.
'The lady who plucks her eyebrows and the one who gets them plucked, they're both cursed by Allah.'
Sheikh Doar's audience
He was referring to the hadith, describing the actions of the Prophet Mohammad, as part of a question and answer session organised by Muslim charity Sisters United.
Taking questions from the girls, Sheikh Doar told them they needed to wear their hijabs loose and with no bright or colourful patterns.
'It cannot be see-through showing skin. The hijab needs to be as plain as possible,' he said.
'It cannot be an imitation of the disbeliever's dress code. It cannot be attracting to the eye. It cannot resemble the dress of men. It can't be a showing-off cloth.'He also warned them they would face criticism about their dress sense from other Muslims and kafirs, a sharia-law term for non-believers.
The sheikh's advice is generally rejected by secular Muslims, who also shun sharia law.