'When anyone of you swears an oath, let him not say: 'What Allah wills and what you will.' Rather let him say: 'What Allah wills and then what you will.'  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا حَلَفَ أَحَدُكُمْ فَلاَ يَقُلْ مَا شَاءَ اللَّهُ وَشِئْتَ وَلَكِنْ لِيَقُلْ مَا شَاءَ اللَّهُ ثُمَّ شِئْتَ  

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.  

أَنَّ رَجُلاً مِنَ الْمُسْلِمِينَ رَأَى فِي النَّوْمِ أَنَّهُ لَقِيَ رَجُلاً مِنْ أَهْلِ الْكِتَابِ فَقَالَ نِعْمَ الْقَوْمُ أَنْتُمْ لَوْلاَ أَنَّكُمْ تُشْرِكُونَ تَقُولُونَ مَا شَاءَ اللَّهُ وَشَاءَ مُحَمَّدٌ وَذَكَرَ ذَلِكَ لِلنَّبِيِّ ﷺ فَقَالَ أَمَا وَاللَّهِ إِنْ كُنْتُ لأَعْرِفُهَا لَكُمْ قُولُوا مَا شَاءَ اللَّهُ ثُمَّ شَاءَ مُحَمَّدٌ حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ الْمَلِكِ بْنِ أَبِي الشَّوَارِبِ حَدَّثَنَا أَبُو عَوَانَةَ عَنْ عَبْدِ الْمَلِكِ عَنْ رِبْعِيِّ بْنِ حِرَاشٍ عَنِ الطُّفَيْلِ بْنِ سَخْبَرَةَ أَخِي عَائِشَةَ لأُمِّهَا عَنِ النَّبِيِّ ﷺ بِنَحْوِهِ