حَدَّثَنَا هِشَامُ بْنُ عَمَّارٍ، حَدَّثَنَا عِيسَى بْنُ يُونُسَ، حَدَّثَنَا الأَجْلَحُ الْكِنْدِيُّ، عَنْ يَزِيدَ بْنِ الأَصَمِّ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏"‏ إِذَا حَلَفَ أَحَدُكُمْ فَلاَ يَقُلْ مَا شَاءَ اللَّهُ وَشِئْتَ ‏.‏ وَلَكِنْ لِيَقُلْ مَا شَاءَ اللَّهُ ثُمَّ شِئْتَ ‏"‏ ‏.‏

It was narrated from Hudhaifah bin Yaman that

a Muslim man saw in a dream that he met a man from among the People of the Book, who said: "What good people you would be if only you were not committing Shirk. For you say: 'What Allah wills and Muhammad wills."' He mentioned that to the Prophet (ﷺ) and he said: "By Allah, I am aware of that. Say: 'What Allah wills then what Muhammad wills."'Another chain from Tufail bin Sakhbarah, the brother of 'Aishah by her mother, from the Prophet (ﷺ), with similar wording.