The client of Usamah ibn Zayd said that he went along with Usamah to Wadi al-Qura in pursuit of his camels. He would fast on Monday and Thursday. His client said to him: Why do you fast on Monday and Thursday, while you are an old man? He said: The Prophet of Allah ﷺ used to fast on Monday and Thursday. When he was asked about it, he said: The works of the servants (of Allah) are presented (to Allah) on Monday and Thursday.  

أَنَّهُ انْطَلَقَ مَعَ أُسَامَةَ إِلَى وَادِي الْقُرَى فِي طَلَبِ مَالٍ لَهُ فَكَانَ يَصُومُ يَوْمَ الاِثْنَيْنِ وَيَوْمَ الْخَمِيسِ فَقَالَ لَهُ مَوْلاَهُ لِمَ تَصُومُ يَوْمَ الاِثْنَيْنِ وَيَوْمَ الْخَمِيسِ وَأَنْتَ شَيْخٌ كَبِيرٌ فَقَالَ إِنَّ نَبِيَّ اللَّهِ ﷺ كَانَ يَصُومُ يَوْمَ الاِثْنَيْنِ وَيَوْمَ الْخَمِيسِ وَسُئِلَ عَنْ ذَلِكَ فَقَالَ إِنَّ أَعْمَالَ الْعِبَادِ تُعْرَضُ يَوْمَ الاِثْنَيْنِ وَيَوْمَ الْخَمِيسِ