Jami` at-Tirmidhi 2198
Hisham narrated that Al-Hasan would say about the Hadith:
"  Morning will come upon a man as a believer, who will be a disbeliever in the evening, and evening will come upon a believer, who will be a disbeliever in the morning" - he said: "Morning would come[upon a man] while his brother's blood, honor and wealth was sacred, and when evening would come, he would consider it lawful for him. And evening would come while his brother's blood, honor and wealth was sacred, and when morning would come, he would  consider it lawful for him."
حَدَّثَنَا صَالِحُ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا جَعْفَرُ بْنُ سُلَيْمَانَ، عَنْ هِشَامٍ، عَنِ الْحَسَنِ، قَالَ كَانَ يَقُولُ فِي هَذَا الْحَدِيثِ ‏
"‏ يُصْبِحُ الرَّجُلُ مُؤْمِنًا وَيُمْسِي كَافِرًا وَيُمْسِي مُؤْمِنًا وَيُصْبِحُ كَافِرًا ‏"‏ ‏.‏ قَالَ يُصْبِحُ الرَّجُلُ مُحَرِّمًا لِدَمِ أَخِيهِ وَعِرْضِهِ وَمَالِهِ وَيُمْسِي مُسْتَحِلاًّ لَهُ وَيُمْسِي مُحَرِّمًا لِدَمِ أَخِيهِ وَعِرْضِهِ وَمَالِهِ وَيُصْبِحُ مُسْتَحِلاًّ لَهُ ‏.‏