saying, 'This man began to build, but could not finish.'

And saying, This man made a start at building and is not able to make it complete.

and say 'Here is a person who began to build and was not able to finish!'

Saying, this man began to build,.... He set out well, he promised great things, and made a considerable bluster and stir, as if he would carry things at once to a very high pitch:
and was not able to finish; it was all noise and talk, and nothing else: falling off from a profession of religion, exposes men to contempt and scorn; such are not only cast out of churches with disgrace, but are despised by men, by wicked men; and are a reproach, a proverb, and a taunt in all places; and even are mocked by devils too.