Brother wants to contest father's will 6 years after our father died

Hi, Me and my brother's late father had made a will where me and my son were the sole beneficiaries (and I was the executor) because my father had given my brother his share through gifts while he was still alive. Our father had told both of us the contents of the will and after his demise (a little over 6 years ago), my brother did not say anything about the will. Now he has run into money issues and is claiming that he will contest the will. He did not say anything then otherwise I would've gotten the will probated then. Now contact with witnesses is also hard since will was made 10 years ago. I read some Supreme Court of India case law relating to limitation act and all of it seems to be about cases where the executor can file for probate upto 3 years after when the right to apply accrues which should be when the interest of the executor is infringed upon rather than at the death of the testator. This makes sense to me. However in my case, my brother would presumably file a declaration suit for the property or claim intestacy and hence for filing of succession certificate now. My question is should such an application be barred by limitations act because if his interest was being infringed upon while he knew I was occupying and leasing out the property, he could've filed a suit from when he knew his "right" was being infringed upon. Thanks