The Prophet ﷺ said: Supplication (du'a') is itself the worship. (He then recited:) "And your Lord said: Call on Me, I will answer you" (xI.60). (Using translation from Abū Dāʾūd 1479)
سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ «إِنَّ الدُّعَاءَ هُوَ الْعِبَادَةُ» ثُمَّ قَرَأَ {وَقَالَ رَبُّكُمُ ادْعُونِي أَسْتَجِبْ لَكُمْ} [غافر 60]