Alḥamdulillāh and the most excellent words of remembrance are: Lā ilāha illallāh. The most excellent invocation is: Praise is for Allah. and the most excellent words of remembrance are: There is none worthy of worship but Allah. Reference: At-Tirmidhi 5/462, Ibn Majah 2/1249, and Al-Hakim who graded it authentic and Ath-Tbahabi agreed 1/503. See Al-Albani, Sahihul-Jami' As-Saghir 1/362.

Allah's Messenger said: "The supplication made between the Adhan and Iqamah is not rejected."

The Prophet said: “The supplication, is worship.” Then he recited: And Your Lord said: “Call upon me, I will respond to you. Verily, those who scorn My worship, they will surely enter Hell humiliated."

“Call upon Allah while being certain of being answered, and know that Allah does not respond to a supplication from the heart of one heedless and occupied by play.”

Abud Darda’ reported God’s Messenger as saying that God most high says, "I am God than whom there is no god, Master of kings, King of kings, in whose hands are the hearts of kings. When men obey me I turn the hearts of kings to them with mercy and gentleness, but when they disobey me I turn their hearts against them with displeasure and vengeance, and they inflict grievous punishment upon them. So do not occupy yourselves with invoking curses on kings, but occupy yourselves with remembrance of me and supplication that I may protect you against your kings.” Abu Nu'aim transmitted it in al-Hilya.

He then commanded him to perform ablution, doing it well, and make this supplication, “O God, I make request of Thee and I turn towards Thee by means of Thy prophet Muhammad, the prophet of mercy. By means of you 1 have turned towards my Lord to accomplish for me this need of mine. O God, make him an intercessor for me.” 1. bika. This would seem here to refer to the Prophet, although by itself it might naturally be taken to refer to God. The sentence which precedes certainly suggests that it must refer to the Prophet, in which case the translation might go, “by means of whom I have turned towards my Lord.” Changes of pronouns in Arabic often present difficulties to the translator. Tirmidhi transmitted it, saying this is a hasan sahih gharib tradition.

"The Messenger of Allah (SAW) said: 'Nothing extends one's life span but righteousness, nothing averts the Divine Decree but supplication, and nothing deprives a man of provision but the sin that he commits.'"

“Nothing increases one’s life span except righteousness and nothing repels the Divine decree except supplication, and a man may be deprived of provision by a sin that he commits.’”

"I asked 'Aishah about a supplication that the Messenger of Allah (saas) used to say. She said that he used to say: 'Allahumma inni a'udhu bika min sharri ma 'amiltu, wa min sharri ma lam a'mal (O Allah, I seek refuge with You from the evil of that which I have done and the evil of that which I have not done).'"

"I heard the Messenger of Allah (SAW) say: 'The best of remembrance is La ilaha illallah (None has the right to be worshipped but Allah), and the best of supplication is Al-Hamdu Lillah (praise is to Allah).'"

Ishaq ibn Abdullah ibn Kinanah reported: Al-Walid ibn Utbah or (according to the version of Uthman) al-Walid ibn Uqbah, the then governor of Medina, sent me to Ibn Abbas to ask him about the prayer for rain offered by the Messenger of Allah (saws). He said: The Messenger of Allah (saws) went out wearing old clothes in a humble and lowly manner until he reached the place of prayer. He then ascended the pulpit, but he did not deliver the sermon as you deliver (usually). He remained engaged in making supplication, showing humbleness (to Allah) and uttering the takbir (Allah is most great). He then offered two rak'ahs of prayer as done on the 'Id (festival).

Abu Dawud said: This is the version of al-Nufail. What is correct is Ibn Utbah's

"The closest that the slave comes to his Lord is when he is prostrating, so invoke Allah much (in prostration)." Reference: Muslim 1/350.

the Messenger of Allah (saws) said: “The best remembrance is: ‘there is none worthy of worship except Allah (Lā ilāha illallāh)’ and the best supplication is: ‘All praise is due to Allah (Al-ḥamdulillāh).’”

Teach me a dua that I may say in my prayer. He said: `Say: O Allah, I have wronged myself greatly and no one forgives sins but you, grant me forgiveness from you and have mercy on me for you are the Oft Forgiving Most Merciful

“I heard the Messenger of Allah (SAW) say: ‘When you offer the prayer for the deceased, supplicate sincerely for him.’”

"Al-Walid bin Uqbah, the governor of Al-Madinah, sent me to ask Ibn Abbas about how the Messenger of Allah would perform Salat Al-Istisqa. I came to him and he said: 'The Messenger of Allah would go out in modest dress, humbly, imploring, until he reached the Musalla. He would not give this Khutbah of yours, rather, he would continue supplication and imploring saying the Takbir, and pray two Rak'ah, just as he would pray for the Eid.'"

“O Messenger of Allah, teach me a supplication that I may supplicate with in my Salat.” He (saws) said: “Say: ‘O Allah, I have wronged myself much, and none forgives sins except You. So forgive me with forgiveness from You, and have mercy upon me, indeed, You are the Forgiving, the Merciful (Allāhumma innī ẓalamtu nafsī ẓulman kathīran wa lā yaghfirudh-dhunūba illā anta faghfirlī maghfiratan min `indika warḥamnī innaka antal-Ghafūrur-Raḥīm).’”

Abu Hurairah (RAA) narrated that the Messenger of Allah (P.B.U.H.) said, “Nothing is more honorable before Allah than supplication.” Related by At-Tirmidhi with a full chain of narrators. Ibn Hibban and Al-Hakim graded it as Sahih;.

'Allahumma! Inni a'udhu bika minal-arba': min 'ilmin la yanfa'u, wa min qalbin la yakhsha'u, wa min nafsin la tashba'u, wa min du'a'in la yusma' [O Allah, I seek refuge with You from four things: From knowledge that is of no benefit, from a heart that does not fear (You), from a soul that is never satisfied, and from a supplication that is not heard].'"