Importance of Dua/Dhikr From the Sunnah
Narrated by Abu Hurairah (Radhi Allahu Anhu): Allah’s Messenger (Sallallahu 'Alayhi wa Sallam) said, "When it is the last third of the night, our Lord, the Blessed, the Superior, descends every night to the heaven of the world and says,
'Is there anyone who invokes Me (demand anything from Me), that I may respond to his invocation; Is there anyone who asks Me for something that I may give (it to) him; Is there anyone who asks My forgiveness that I may forgive him?'"(Al-Bukhari)
The Messenger of Allah (Sallallahu 'Alayhi wa Sallam) said: “The comparison of the one who remembers Allah and the one who does not remember Allah, is like that of the living and the dead. (Al-Bukhari and Muslim)
Narrated by Abu Hurairah (Radhi Allahu Anhu): Allah’s Messenger (Sallallahu 'Alayhi wa Sallam) said, "For every prophet there is one (special invocation) that will not be rejected) with which he appeals (to Allah), and I want to keep such an invocation for interceding for my followers in the Hereafter." (Al-Bukhari)
Narrated by Abu Hurairah (Radhi Allahu Anhu): I heard Allah’s Messenger (Sallallahu 'Alayhi wa Sallam) saying." By Allah! I ask for forgiveness from Allah and turn to Him in repentance more than seventy times a day." (Al-Bukhari)
Al-Agharr al-Muzani (Radhi Allahu Anhu) who was from amongst the Companions of Allah's Messenger (Sallallahu Alayhi wa Sallam) reported that Ibn 'Umar (Radhi Allahu Anhu) stated to him that Allah's Messenger (Sallallahu Alayhi wa Sallam) said: “O people, seek repentance from Allah. Verily, I seek repentance from Him a hundred times a day.” (Muslim)
Abu Dharr (Radhi Allahu Anhu) reported that Allah's Messenger (Sallallahu Alayhi wa Sallam) said: “There is no believing servant who supplicates for his brother behind his back (in his absence) that the Angels do not say: The same be for you too.” (Muslim)
Abu Hurairah (Radhi Allahu Anhu) reported Allah's Messenger (Sallallahu Alayhi wa Sallam) as saying: “He who seeks repentance (from the Lord) before the rising of the sun from the west (before the Day of Resurrection), Allah turns to him with Mercy.” (Muslim)
Narrated by Anas bin Malik (Radhi Allahu Anhu): Allah’s Messenger (Sallallahu 'Alayhi wa Sallam) said, "Allah is more pleased with the repentance of His slave than anyone of you is pleased with finding his camel which he had lost in the desert." (Al-Bukhari)
Imam Ahmad also recorded Abu Said (Radhi Allahu Anhu) saying that the Prophet (Sallallahu Alayhi wa Sallam) said:
No Muslim supplicates to Allah with a Dua that does not involve sin or cutting the relations of the womb, but Allah will grant him one of the three things. He will either hasten the response to his supplication, save it for him until the Hereafter, or would turn an equivalent amount of evil away from him.'') They said, "What if we were to recite more (Dua).'' (Imam Ahmad)
Abu Hurayrah (Radhi Allahu Anhu) narrated, the Messenger of Allah (Sallallahu Alayhi wa Sallam) said:
Three persons will not have their supplication rejected: the just ruler, the fasting person until breaking the fast, and the supplication of the oppressed person, for Allah raises it above the clouds on the Day of Resurrection, and the doors of heaven will be opened for it, and Allah says, `By My grace! I will certainly grant it for you, even if after a while.' (At-Tirmidhi and ibn Majah)
Wa Alaikum Salam wa Rahmatullahi wa Barakatuhu