Cap on pension contributions, personal or employer

My heart sank when a I got a call from a client, who pays himself £8,000 salary, telling me his IFA has suggested he makes an employer pension contribution of £40k before 5 April

I don't pretend to be a specialist in this area, so I wanted to refer both myself and him to a table that would show caps and limits of what was and wasn't possible on a personal and/or employer basis. I have searched but can't find anything suitable even on the Pension Advisory Service website. Can anyone offer a link or assistance?

Edit - I am aware of the £50k annual allowance, that tax relief is limited to 100% earnings, but not sure about was 'earnings' means or the practical implications of exceeding earnings while staying under the annual allowance cap.