وإن ذَرَعَهُ القَيءُ: لم يُفطِرْ.
Translation: If vomiting overtakes him involuntarily, the fast is not invalidated.
The Arabic phrase dharaʿahu al-qayʾ means that vomiting overcame the person involuntarily. The vomiting was not deliberately induced, so the fast remains intact under this line.
For example, an unexpected episode caused by nausea falls under involuntary vomiting. It should not be confused with a person intentionally bringing up vomit.