Anas reported God’s Messenger 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