Residential house gifted with registered gift deed from father to son. after some time father cancelled/revoked the gift and executed a sale deed in favour of other son. Pl let me know is it valid deed that without knowldge of donee, the donar cancelled and execution of sale deed

What are the terms of the gift deed, check whether it is a onerous gift. 

Onerous Gift
'Onerous gift' is a gift made subject to certain charges imposed by the donor on the donee. The principle behind this is that he who accepts the benefit of a transaction must also accept the burden of the same. This section, being an embodiment of a rule of equity, applies equally to Hindus and Mahomedans. For acceptance of an onerous gift, acceptance of the gift itself is sufficient; there need not be any separate and express acceptance of the onerous condition also at the same time. The acceptance of the gift will carry with it the acceptance of the onerous condition also, even though at the time of the gift the donee was not aware of such condition, specially where the onerous condition is of a trifling nature (payment of Rs. 5 as monthly maintenance to a certain person for life).

If the gift is accepted by the donee son the revocation is void, but the gift is not acted upon the donar is having right to revoke the same without the knowledge of the donee and the same is valid as per section 122 of T.P Act

i posted one topic almost same as previous one which has been not included.the true spirit of the topic was whetrer a gift deed be conditional or not.replied already ---yes it can be conditional in certain cases.am i correct?