The Messenger of Allah ﷺ said, "Supplication is itself worship." Then he recited "Call upon Me, I will respond to you. Indeed, those who are too proud to worship Me..." [Ghafir 40:60].
حدثنا عبد الرزاق أخبرنا سفيان عن الأعمش ومنصور عن ذر عن يسيع الكندي
أن رسول الله ﷺ قال إن الدعاء هو العبادة ثم قرأ {ادعوني أستجب لكم إن الذين يستكبرون عن عبادتي}
Its isnad is sahih. Yasi bin Madan Hadrami Kindi is a trustworthy narrator among the Tabiin, and his hadith appears in the Sunan collections. The hadith was narrated by Abu Dawud (2/76, no. 1479), Tirmidhi (5/211, no. 2969), who said it is hasan sahih, and Ibn Majah (2/1258, no. 3828).