How did the oaths of the Prophet (ﷺ) use to be?
حَدَّثَنَا عُمَرُ بْنُ حَفْصٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا الأَعْمَشُ، عَنِ الْمَعْرُورِ، عَنْ أَبِي ذَرٍّ، قَالَ انْتَهَيْتُ إِلَيْهِ وَهُوَ يَقُولُ فِي ظِلِّ الْكَعْبَةِ " هُمُ الأَخْسَرُونَ وَرَبِّ الْكَعْبَةِ، هُمُ الأَخْسَرُونَ وَرَبِّ الْكَعْبَةِ " قُلْتُ مَا شَأْنِي أَيُرَى فِيَّ شَىْءٌ مَا شَأْنِي فَجَلَسْتُ إِلَيْهِ وَهْوَ يَقُولُ، فَمَا اسْتَطَعْتُ أَنْ أَسْكُتَ، وَتَغَشَّانِي مَا شَاءَ اللَّهُ، فَقُلْتُ مَنْ هُمْ بِأَبِي أَنْتَ وَأُمِّي يَا رَسُولَ اللَّهِ قَالَ " الأَكْثَرُونَ أَمْوَالاً، إِلاَّ مَنْ قَالَ هَكَذَا وَهَكَذَا وَهَكَذَا ".
Narrated Abu Dhar: I reached him (the Prophet (ﷺ) ) while in the shade of the Ka`ba; he was saying, "They are the losers, by the Lord of the Ka`ba! They are the losers, by the Lord of the Ka`ba!" I said (to myself ), "What is wrong with me? Is anything improper detected in me? What is wrong with me? Then I sat beside him and he kept on saying his statement. I could not remain quiet, and Allah knows in what sorrowful state I was at that time. So I said, ' Who are they (the losers)? Let My father and mother be sacrificed for you, O Allah's Messenger!" He said, "They are the wealthy people, except the one who does like this and like this and like this (i.e., spends of his wealth in Allah's Cause).