Relief cannot be granted unless prayed.

Good question. There are many judgments on the subject and a very cogent argument to blunt prayers put in arguments which are missing in the petition/suit. The best on the subject is:

Manohar Lal v. Ugrasen AIR 2010 SC 2210.  See link here https://indiankanoon.org/doc/116086329/.   The judgments referenced in it provide more than sufficient material to convince any Judge.

Many wives tend to write one petition and then digress into cock-and-bull stories and seek totally new relief which was never prayed for in the petition itself. This judgment and the other Supreme Court judgments referenced in it makes it unambiguously clear that "Relief cannot be granted unless prayed."  While I am fully aware of all the related cases as I used them in my own arguments a few years back, I am curious as to why you did not do a search on the net with the exact words used by you.  Google does not give the above judgment but does give some which are referenced in this judgments from which you could have got to this judgment.  Not  intended to be a rude comment, just a query out of curiosity.