Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
tirmidhi:2969 – Hannād > Abū Muʿāwiyah > al-Aʿmash > Dhar > Yusayʿ al-Kindī > al-Nuʿmān b. Bashīr

from the Prophet ﷺ regarding Allah's saying: Your Lord said: Invoke Me, I shall respond to you (40:60, it appears that the author intended to apply it to Al-Baqarah 2:186). - he said: "The supplication is the worship." And he recited: 'Your Lord said: Invoke Me, I shall respond to you.' up to His saying: 'in humiliation.'"  

Abū ʿĪsá said that this Ḥadīth is Ḥasan-Ṣaḥīḥ.
الترمذي:٢٩٦٩ – حَدَّثَنَا هَنَّادٌ حَدَّثَنَا أَبُو مُعَاوِيَةَ عَنِ الأَعْمَشِ عَنْ ذَرٍّ عَنْ يُسَيْعٍ الْكِنْدِيِّ عَنِ النُّعْمَانِ بْنِ بَشِيرٍ

عَنِ النَّبِيِّ ﷺ فِي قَوْلِهِ (وَقَالَ رَبُّكُمُ ادْعُونِي أَسْتَجِبْ لَكُمْ ) قَالَ الدُّعَاءُ هُوَ الْعِبَادَةُ وَقَرَأَ ( وَقَالَ رَبُّكُمُ ادْعُونِي أَسْتَجِبْ لَكُمْ ) إِلَى قَوْلِهِ ( دَاخِرِينَ )  

قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ

See similar narrations below:

Collected by Abū Dāwūd, Nasāʾī's Kubrá
abudawud:1479 – Ḥafṣ b. ʿUmar > Shuʿbah > Manṣūr > Dhar > Yusayʿ al-Ḥaḍramī > al-Nuʿmān b. Bashīr

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).  

أبو داود:١٤٧٩ – حَدَّثَنَا حَفْصُ بْنُ عُمَرَ حَدَّثَنَا شُعْبَةُ عَنْ مَنْصُورٍ عَنْ ذَرٍّ عَنْ يُسَيْعٍ الْحَضْرَمِيِّ عَنِ النُّعْمَانِ بْنِ بَشِيرٍ

عَنِ النَّبِيِّ ﷺ قَالَ الدُّعَاءُ هُوَ الْعِبَادَةُ { قَالَ رَبُّكُمُ ادْعُونِي أَسْتَجِبْ لَكُمْ }  

nasai-kubra:11400 – Sūwayd b. Naṣr > ʿAbdullāh > Shuʿbah > Manṣūr > Dhar > Hannād b. al-Sarī > Abū Muʿāwiyah > al-Aʿmash > Dhar > Yusayʿ > al-Nuʿmān b. Bashīr

[Machine] About the Prophet ﷺ regarding the saying of Allah, "And your Lord says, 'Call upon Me; I will respond to you'" [Quran 40:60], he said, "Supplication is worship." Then he recited, "Call upon Me; I will respond to you. Indeed, those who disdain My worship will enter Hell [rendered] contemptible." [Quran 40:60] The wording is by Hannad.  

الكبرى للنسائي:١١٤٠٠ – أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ قَالَ أَخْبَرَنَا عَبْدُ اللهِ عَنْ شُعْبَةَ عَنْ مَنْصُورٍ عَنْ ذَرٍّ وَأَخْبَرَنَا هَنَّادُ بْنُ السَّرِيِّ عَنْ أَبِي مُعَاوِيَةَ عَنِ الْأَعْمَشِ عَنْ ذَرٍّ عَنْ يُسَيْعٍ عَنِ النُّعْمَانِ بْنِ بَشِيرٍ

عَنِ النَّبِيِّ ﷺ فِي قَوْلِ اللهِ ﷻ {وَقَالَ رَبُّكُمُ ادْعُونِي أَسْتَجِبْ لَكُمْ} [غافر 60] قَالَ «الدُّعَاءُ هُوَ الْعِبَادَةُ» ثُمَّ قَرَأَ {ادْعُونِي أَسْتَجِبْ لَكُمْ إِنَّ الَّذِينَ يَسْتَكْبِرُونَ عَنْ عِبَادَتِي سَيَدْخُلُونَ جَهَنَّمَ دَاخِرِينَ} [غافر 60] اللَّفْظُ لِهَنَّادٍ