Allah (Subhaanahu wa Ta’aala) says:
{Therefore remember Me, I will remember you and be grateful to Me, and never be ungrateful to me}, [Soorah al-Baqarah, Aayah 152]

{O you who believe! Remember Allah with much remembrance}, [Soorah al-Ahzaab, Aayah 41]
{And for men and women who engage much in Allah’s remembrance, for them has Allah prepared forgiveness and great reward}, [Soorah al-Ahzaab, Aayah 35]

{And bring your Lord to remembrance in your [very] soul, with humility and remember without loudness in words, in the mornings and evenings; and be not of those who are unheedful}, [Soorah al-A’raaf, Aayah 205]

The Prophet (sal-Allaahu `alayhe 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-Bukhaaree with al-Fat.h 11/208 and Muslim 1/539]

He (sal-Allaahu `alayhe wa sallam) also said:
((Should I not inform you of the best of deeds, and the most sanctifying of deeds before your Lord, which does more to raise your positions [with Him], and are better for you than the disbursement of gold and money or battle with the enemy?))
They [the companions] said: “Indeed! Inform us.”
He (sal-Allaahu `alayhe wa sallam) then said:
((Remembrance of Allah (Subhaanahu wa Ta’aala))), [at-Tirmidhee 5/459 and Ibn Maajah 2/1245, see: Saheeh Ibn Maajah 2/316 and Saheeh at-Tirmidhee 3/139]

The Prophet (sal-Allaahu `alayhe wa sallam) also said:
((Allah (Subhaanahu wa Ta’aala) says: “Indeed I am as My servant presumes Me to be, and I am with him when he remembers Me, so if he remembers Me to himself I remember him to Myself, and if he remembers Me amongst a company I remember him amongst a company greater than it, and if he draws near to Me the span of a hand I draw near to him the span of an arm, and if he draws near to Me the span of an arm I draw near to him the span of two outstretched arms, and if he takes a step towards Me I hastily step towards him”)), [al-Bukhaaree 8/171 and Muslim 4/2061, this specific wording is related by al-Bukhaaree]

On the authority of ‘Abdullaah Ibn Busr (radhi-yallaahu ‘anhu): “A man said to the Prophet (sal-Allaahu `alayhe wa sallam): “O Messenger of Allah, the rites of Islam are much for me, so tell me of something that I might hold fast to”
He (sal-Allaahu `alayhe wa sallam) said:
((Let not your tongue cease from the remembrance of Allah)), [at-Tirmidhee 5/458 and Ibn Maajah 2/1246, see: Saheeh at-Tirmidhee 3/139 and Saheeh Ibn Maajah 2/317]

The Prophet (sal-Allaahu `alayhe wa sallam) also said:
((Whoever recites a letter of Allah’s Book has for it, a merit and ten more like it, not to say that alif, laam, meem are one letter but rather alif is a letter, laam is a letter and meem is a letter)), [at-Tirmidhee 5/175, see: Saheeh at-Tirmidhee 3/9 and Saheeh al-Jaami’ as-Sagheer 5/340]

The Prophet (sal-Allaahu `alayhe wa sallam) also said:
((Whoever takes a seat and fails to remember Allah, has incurred upon himself a loss from Allah, and whoever lies down [relaxes] and fails to remember Allah, has incurred upon himself a loss from Allah)), [Abu Daawood 4/264 and others, see: Saheeh al-Jaami’ 5/342.]

Please note: All supplications are taken from the English translation of Hisnul-Muslim (“Fortification of the Muslim through Remembrance and Supplication from the Qur.aan and Sunnah”), as published by Invitation To Islam.