And ask whom We sent before you of Our Messengers:"Did We ever appoint gods to be worshipped besides the Most Gracious?"means, `all the Messengers called their people to the same as that to which you are calling mankind, namely the worship of Allah Alone with no partner or associate, and they forbade the worship of idols and false gods.'This is like the Ayah:وَلَقَدْ بَعَثْنَا فِى كُلِّ أُمَّةٍ رَّسُولاً أَنِ اعْبُدُواْ اللَّهَ وَاجْتَنِبُواْ الْطَّـغُوتَAnd verily, We have sent among every Ummah (nation) a Messenger (proclaiming):"Worship Allah, and avoid all false deities." (16:36)Mujahid said that Abdullah bin Mas`ud recited it:وَاسْأَلْ الَّذِينَ أَرْسَلْنَا إِ لَيْهِمْ قَبْلِكَ مِن رُّسُلِنَا (And ask those whom We sent before you of Our Messengers).This was narrated by Qatadah, Ad-Dahhak and As-Suddi from Ibn Mas`ud, may Allah be pleased with him.Yet this appears to be an explanation rather than an alternate version of recitation. And Allah knows best