Supplication or Dua to Allah is of paramount importance in Islam. The benefits of supplication are immense as are its virtues. Allah Says
وَإِذَا سَأَلَكَ عِبَادِي عَنِّي فَإِنِّي قَرِيبٌ أُجِيبُ دَعْوَةَ الدَّاعِ إِذَا دَعَانِ فَلْيَسْتَجِيبُواْ لِي وَلْيُؤْمِنُواْ بِي لَعَلَّهُمْ يَرْشُدُونَ
When My servants ask thee concerning Me, I am indeed close (to them): I listen to the prayer of every
suppliant when he calleth on Me: Let them also, with a will, Listen to My call, and believe in Me: That they may walk in the right way.
[Surah Al-Baqara : Ayah 186]
Allah Says
ادْعُواْ رَبَّكُمْ تَضَرُّعًا وَخُفْيَةً إِنَّهُ لاَ يُحِبُّ الْمُعْتَدِينَ
Call on your Lord with humility and in private: for God loveth not those who trespass beyond bounds.
[Surah Al-Araaf : Ayah 55]
Allah's Messenger Muhammad (Sal-allahu-alleihi-wasallam) said:
"Shall I introduce to you a weapon which will protect you both from the evils of enemies and increase your sustenance? He said: Call your Lord day and night, for “Dua” is the weapon of a believer.”
[ Sahih Bukhari]
Allah's Messenger Muhammad (Sal-allahu-alleihi-wasallam) said:
“Dua” and afflictions challenge each other until the day of Judgment, yet “Dua” comes out victoriously even if the afflictions are certain to happen.”
[ Sahih Bukhari]