The oath to be taken by an ANC member is in rule 4.17 of the ANC Constitution; it is to be taken in a language he or she knows well.

“I, […], solemnly declare that I will abide by the aims and objectives of the African National Congress as set out in the Constitution, the Freedom Charter and other duly adopted policy positions, that I am joining the Organisation voluntarily and without motives of material advantage or personal gain, that I agree to respect the Constitution and the structures and to work as a loyal member of the Organisation, that I will place my energies and skills at the disposal of the Organisation and carry out tasks given to me, that I will work towards making the ANC an even more effective instrument of liberation in the hands of the people, and that I will defend the unity and integrity of the Organisation and its principles, and combat any tendency towards disruption and factionalism”. 

www.anc.org.za/docs/const/2012/const.pdf