When something pleasing happens
When something pleased the Prophet, he would say:
الْحَمْدُ لِلَّهِ الَّذِي بِنِعْمَتِهِ تَتِمُّ الصَّالِحَاتُ
Al-ḥamdu li-llāhi alladhī bi-niʿmatihi tatimmu aṣ-ṣāliḥāt
All praise is for Allah, by whose grace good things are brought to completion.
When something displeasing happens
When something displeased him, he would say:
الْحَمْدُ لِلَّهِ عَلَى كُلِّ حَالٍ
Al-ḥamdu li-llāhi ʿalā kulli ḥāl
All praise is for Allah in every circumstance.