Al-Kāfi - Volume 4 > Excellence of Performing Salat (Prayer) in Masjid al-Haram (the Sacred Masjid) and the Best Place Therein
Hadith #4

4ـ أَحْمَدُ بْنُ مُحَمَّدٍ عَنْ عَلِيِّ بْنِ الْحَكَمِ عَنِ الْكَاهِلِيِّ قَالَ كُنَّا عِنْدَ أَبِي عَبْدِ الله (عَلَيْهِ السَّلاَم) فَقَالَ أَكْثِرُوا مِنَ الصَّلاةِ وَالدُّعَاءِ فِي هَذَا الْمَسْجِدِ أَمَا إِنَّ لِكُلِّ عَبْدٍ رِزْقاً يُجَازُ إِلَيْهِ جَوْزاً.

4. Ahmad ibn Muhammad has narrated from Ali ibn al-Hakam from al-Kahiliy who has said the following: “Once we were with abu ‘Abd Allah, ‘Alayhi al-Salam, and he said, ‘You must say a great deal of Salat (prayer) and supplications in this Masjid. There is no doubt that for every servant (of Allah) there is a certain share of sustenance that is passed to him undeniably.’”