First possibility cannot be justified as gap of khaibar and HP(saww)s shahadat is 4 years and effect of poison cannot be stretched for 4 years… Second possibility has higher chance. With regards to shahadat we have one tradition from beharul Anwar, Vol. 45 that Imam Hasan as says….. الْحُسَيْنُ بْنُ أَبِي الْعَلَاءِ (١) عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ(ع)قَالَ الْحَسَنُ بْنُ عَلِيٍّ(ع)لِأَهْلِ بَيْتِهِ يَا قَوْمِ إِنِّي أَمُوتُ بِالسَّمِّ كَمَا مَاتَ رَسُولُ اللَّهِ ص