Mishkat al-Masabih
Anas reported God’s messsenger as saying, “Supplication is the pith of worship.” Tirmidhi transmitted it.
وَعَنْ أَنَسٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «الدُّعَاءُ مُخُّ الْعِبَادَةِ» . رَوَاهُ التِّرْمِذِيّ
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