I've heard a grammar rule which is, if there is any verb followed by a preposition except the 'to' preposition, the verb must have a 'ing'.
As example, I've this sentence:
I am going for playing.
Where the 'play' verb is in 'ing' form.
But in this sentence:
I am going to play.
the 'play' verb is in normal form.
I just want to know that is the rule correct? If correct then is there any other exceptional preposition like 'to'?