Surah Al Momin ayat # 60 : Your Lord has said: "Call to Me that I may answer your call. Surely those who disdain worshipping Me will enter Hell, disgraced."

The reality of du`a' (supplication) and its merits, levels and conditions of acceptance
In the last verse cited in this unit, it was said:

وَقَالَ رَ‌بُّكُمُ ادْعُونِي أَسْتَجِبْ لَكُمْ ۚ إِنَّ الَّذِينَ يَسْتَكْبِرُ‌ونَ عَنْ عِبَادَتِي سَيَدْخُلُونَ جَهَنَّمَ دَاخِرِ‌ينَ
And your Lord has said, “Call Me, I will respond to you. Definitely those who show arrogance against worshipping Me shall enter Jahannam, disgraced. - 40:60.

Literally, du'a means to call, and it is frequently used to call for something needed. On occasions, the dhikr of Allah (acts devoted to His remembrance) is also referred to as du'a. This verse confers a special honor on the large community of the followers of the Holy Prophet صلی اللہ علیہ وسلم when they were ordered to make dua' with the assurance that it would be answered. And whoever does not make a prayer has been warned of punishment.

Qatadah reports from Ka'b Ahbar that earlier this used to be peculiar to prophets, as they were the ones who were ordered by Allah Ta’ala that they should make dua' and He would answer. Now, it is the distinction of the followers of the Holy Prophet صلی اللہ علیہ وسلم (popularly identified as Ummah Muhammadiyyah) that this order was universalized for his entire Ummah. (IbnKathir)

Explaining this verse, Sayyidna Nu`man Ibn Bashir رضی اللہ تعالٰی عنہ narrated a Hadith that the Holy Prophet صلی اللہ علیہ وسلم said: اِنَّ الدُّعَآء ھُو العِبَادۃ (Surely, prayer is worship on its own) and then supported it by reciting this verse: إِنَّ الَّذِينَ يَسْتَكْبِرُ‌ونَ عَنْ عِبَادَتِي, (Definitely those who show arrogance against worshipping Me shall enter Jahannam, disgraced.) (reported by Imam Ahmad, Tirmidhi, Nasa'i, Abu Dawud and others - Ibn Kathir)