The Prophet ﷺ said: if one has a sudden attack of vomiting while one is fasting, no atonement is required of him, but if he vomits intentionally he must make atonement.  

قَالَ رَسُولُ اللَّهِ ﷺ مَنْ ذَرَعَهُ قَىْءٌ وَهُوَ صَائِمٌ فَلَيْسَ عَلَيْهِ قَضَاءٌ وَإِنِ اسْتَقَاءَ فَلْيَقْضِ  

the Prophet said: "Whoever is overcome by vomiting, then he is not required to make up (the fast), and whoever vomits on purpose, then he must make it up."  

أَنَّ النَّبِيَّ ﷺ قَالَ مَنْ ذَرَعَهُ الْقَىْءُ فَلَيْسَ عَلَيْهِ قَضَاءٌ وَمَنِ اسْتَقَاءَ عَمْدًا فَلْيَقْضِ قَالَ وَفِي الْبَابِ عَنْ أَبِي الدَّرْدَاءِ وَثَوْبَانَ وَفَضَالَةَ بْنِ عُبَيْدٍ  

Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to say, "If some one makes himself vomit while he is fasting he has to make up a day, but if he cannot help vomiting he does not have to make up anything."  

أَنَّهُ كَانَ يَقُولُ مَنِ اسْتَقَاءَ وَهُوَ صَائِمٌ فَعَلَيْهِ الْقَضَاءُ وَمَنْ ذَرَعَهُ الْقَىْءُ فَلَيْسَ عَلَيْهِ الْقَضَاءُ  

[Machine] The Messenger of Allah ﷺ said, "Whoever is able to endure should fulfil it (the command of Allah) and whoever is weak in enduring, they should fulfill it whatever they are able to bear."  

قَالَ رَسُولُ اللهِ ﷺ مَنْ ذَرَعَهُ الْقَيْءُفَلَيْسَ عَلَيْهِ قَضَاءٌ وَمَنْ اسْتَقَاءَ فَلْيَقْضِ  

[Machine] The Messenger of Allah ﷺ said: "Whoever vomits involuntarily while fasting, there is no need for them to make up for the fast. But whoever deliberately induces vomiting, they must make up for the fast."  

قَالَ رَسُولُ اللَّهِ ﷺ «مَنْ ذَرَعَهُ الْقَيْءُ وَهُوَ صَائِمٌ فَلَيْسَ عَلَيْهِ قَضَاءٌ وَمَنِ اسْتَقَاءَ فَلْيَقْضِ»  

The Prophet ﷺ said: if one has a sudden attack of vomiting while one is fasting, no atonement is required of him, but if he vomits intentionally he must make atonement. (Using translation from Abū Dāʾūd 2380)   

أَنْ يَقْضِيَ وَإِنْ كَانَ ذَرَعَهُ الْقَيْءُ وَهُوَ صَائِمٌ فَلَيْسَ عَلَيْهِ الْقَضَاءُ»