There is a folk proverb: nothing is difficult in the world, but you can't tell who created it if you set your mind on it. It has been circulated among the people.

Anyway, Bodhi did say so. What he said to the Monkey King in The Journey to the West showed that the language had a pattern as late as the Ming Dynasty.

Upstairs, you said that what Chairman Mao said may be that the chairman has great influence. But in fact, I don't know that the chairman often likes to quote classic sentences and quotations, including many of his poems, and some of them are directly or indirectly quoted. For example, Wei Wu waved a whip and left a legacy in Jieshi in the East.

Officially, he may have said in the editorial of People's Daily on New Year's Day in 1976 that nothing is impossible to a willing mind. This is also a borrowed proverb, so the source of this sentence is not chairman.