I do not know whether it was because of the fasting (or for any other reason) that he (the Holy Prophet) refused to accept that. She raised her voice and showed annoyance to him.
انْطَلَقَ رَسُولُ اللَّهِ ﷺ إِلَى أُمِّ أَيْمَنَ فَانْطَلَقْتُ مَعَهُ فَنَاوَلَتْهُ إِنَاءً فِيهِ شَرَابٌ قَالَ فَلاَ أَدْرِي أَصَادَفَتْهُ صَائِمًا أَوْ لَمْ يُرِدْهُ فَجَعَلَتْ تَصْخَبُ عَلَيْهِ وَتَذَمَّرُ عَلَيْهِ