Explanation

Saadat Khan Burhan-ul-Mulk was appointed Subahdar of Awadh in 1722 and founded the autonomous Awadh state; he was its first Nawab. Safdarjung, his nephew and successor (ruled 1739-54), was the one who later obtained the imperial office of Wazir-ul-Mamalik (Wazir of the Mughal empire), which is why the two are confused. The first Nawab of Awadh itself was therefore Saadat Khan, not Safdarjung. The previously keyed answer is corrected from Safdarjung to Saadat Khan.