[tewall]

Your friends were right. Pushing is terrible. Here's the differences between pushing and a regular bet:

1)You push.
a)With a hand like the one he has, he calls, just like he did.
b)With a hand you have crushed, he folds.

2)You make a smaller bet, he goes all-in, and you call. Then you are playing against the same hands as in a), plus you are also playing against the hands in b). So you chose a way of playing which gives you no overlay, as opposed to a way that does.

There's also the possibility that he will fold if you push, but his turning down a coin-flip in order rather than your getting into a situation where over half the time you have him crushed is not nearly as good for you as your getting all the chips in with much the better of it most of the time.

This isn't close.

Checking seems as viable as pushing, although not as good as his going over the top to your bet. If you check, and a spade doesn't come, and some card comes, like an Ace or the board pairs which you know doesn't help him, and he goes all-in, you can call with a bigger overlay than you get by pushing now. The point is, there are more non-scare cards than what you originally mentioned, because, according to your description, you know he doesn't a number of cards such as an Ace or anything pairing the board (and maybe some others).