QUOTE
To sum up: the fact that Arab leaders of the nationalist movement sold land to Jews was well-known in the Arab community. The political leadership tried unsuccessfully to suppress this information. The subject came alive when Lewis French stated in a memorandum to the Government that certain members of the Moslem Supreme Council had sold land to Jews and that the Arab leadership had no objection to such sales of surplus land.


excerpted from: The Claim of Dispossession : Jewish Land Settlement and the Arabs, 1878-1948 by Arieh L Avneri

got to this source for a list of particulars. ie those who knowingly sold land to zionists.

here are some supporting quotes

King Abdallah, My Memoirs Completed, (London, Longman Group, Ltd., 197, pp. 88-89.
In his memoirs, Transjordan's King Abdullah wrote:


QUOTE
It is made quite clear to all, both by the map drawn up by the Simpson Commission and by another compiled by the Peel Commission, that the Arabs are as prodigal in selling their land as they are in useless wailing and weeping (author's emphasis).


from the Peel Commission: Palestine Royal Commission (1937), pp. 241-242.


QUOTE
The Peel Commission's report found that Arab complaints about Jewish land acquisition were baseless. It pointed out that "much of the land now carrying orange groves was sand dunes or swamp and uncultivated when it was purchased....there was at the time of the earlier sales little evidence that the owners possessed either the resources or training needed to develop the land." Moreover, the Commission found the shortage was "due less to the amount of land acquired by Jews than to the increase in the Arab population." The report concluded that the presence of Jews in Palestine, along with the work of the British Administration, had resulted in higher wages, an improved standard of living and ample employment opportunities.