1. after great grandfather died, his 4 sons orally partitioned the properties among themselves
2. two sons then sold the property which had come to their share to the elder son of one of them
3. under Muslim law the shares of the legal heirs of the deceased person are fixed
4. there are 2 categories of legal heirs - sharers and residuaries
5. after the legal heirs in sharers category have taken their respective fixed shares, the legal heirs of residuary category can take their shares
6. in your case your uncle was required to challenge the sale between A and B to B's elder son, within 3 years of attaining majority
7. he did nothing of that sort
8. so his claim will be barred by limitation
9. to overcome that he says that he will file for partition - but if he does then you have to take the stand that firstly he has to prove whether he had any fixed share in the properties of your great grandfather as a legal heir and secondly that under the garb of partition suit he is trying to challenge the sale agreement between A&B in favour of B's elder son, after a lapse of about 34 years (which is clearly barred by limitation)