Edward Winter, the chess historian, at the end of his page about Mikhail Tal asks the same question:
As shown in A Unique Chess Writer, page 171 of Dimitrije Bjelica’s
Wonderful world of chess quotes Mikhail Tal:
‘There are two kind of sacrifices – the corrects ones, and mine’s.’
Before being tossed into the Bjelica mangling machine, the Tal quote
was something like:
‘There are two kinds of sacrifices – sound ones, and mine.’
We write ‘something like’ because other wordings can be found, such as
‘two types of sacrifice’, but the above version is what Anthony Saidy
gave on page 303 of the June 1973 Chess Life & Review. However, he
merely reported there that Tal ‘once said’ it.
Chess literature teems with things that players purportedly ‘once
said’, ‘said on one occasion’, ‘used to say’, ‘liked to say’ and other
vague variants, but what is the truth about the remark ascribed to
Tal? When did he say, or write, such a thing, and in which language?
When was it first recorded in print? What was the context? Did it
relate to a specific game? What indication, if any, did Tal give that
such a statement was made in jest (or, as anecdotalists like to say,
‘with a twinkle in his eye’)?
So earliest source for this quotation is Saidy's article in Chess Life & Review, but even this one is based on "once said".