After salam

Astaghfirullāh (three times) Allāhumma antas-salām, wa minkas-salām, tabārakta yā dhal-Jalāli wal-'Ikrām. I seek the forgiveness of Allah (three times). O Allah, You are Peace and from You comes peace. Blessed are You, O Owner of majesty and honor. Reference: Muslim 1/414.
Lā 'ilāha 'illallāh, waḥdahu lā sharīka lah, lahu ‘l-mulku wa lahu ‘l-ḥamd, wa huwa `alā kulli shay'in qadīr, Allāhumma lā māni`a limā 'a`tayt, wa lā mu`tiya limā mana`t, wa lā yanfa`u dhal-jaddi minkal-jadd. None has the right to be worshipped but Allah alone, He has no partner, His is the dominion and His is the praise, and He is Able to do all things. O Allah, there is none who can withhold what You give, and none may give what You have withheld, and the might of the mighty person cannot benefit him against You. Reference: Al-Bukhari 1/255, Muslim 1/414.
Lā 'ilāha 'illallāh, waḥdahu lā sharīka lah, lahul-mulku, wa lahul-ḥamd, wa huwa `alā kulli shay'in qadīr. Lā ḥawla wa lā quwwata 'illā billāh, lā 'ilāha 'illallāh, wa lā na`budu 'illā 'iyyāh, lahun-ni`matu wa lahul-faḍl, wa lahuth-thanā'ul-ḥasan, lā 'ilāha 'illallāh, mukhliṣīna lahud-dīn, wa law karihal-kāfirūn. None has the right to be worshipped but Allah alone, He has no partner, His is the dominion and His is the praise and He is Able to do all things. There is no power and no might except by Allah. None has the right to be worshipped but Allah, and we do not worship any other besides Him. His is grace, and His is bounty, and to Him belongs the most excellent praise. None has the right to be worshipped but Allah. (We are) sincere in making our religious devotion to Him, even though the disbelievers may dislike it. Reference: Muslim 1/415.
Subḥānallāh, walḥamdu lillāh, wallāhu 'akbar, (each said thirty-three times) Lā 'ilāha 'illallāh waḥdahu lā sharīka lahu, lahul-mulku wa lahul-ḥamd wa huwā`lā kulli shay'in qadīr. Glory is to Allah, and praise is to Allah, and Allah is the Most Great. (each said thirty-three times) None has the right to be worshiped but Allah alone, He has no partner, His is the dominion and His is the praise and He is Able to do all things. Reference: Muslim 1/418, Whoever says this after every prayer will be forgiven his sins even though they be as the foam of the sea.
Bismillāhir-Raḥmānir-Raḥīm. Qul huwallāhu aḥad. Allāhuṣ-ṣamad. Lam yalid wa lam yūlad. Wa lam yakun lahu kufuwan aḥad. Bismillāhir-Raḥmānir-Raḥīm. Qul a`ūdhu birabbil-falaq. Min sharri mā khalaq. Wa min sharri ghāsiqin idhā waqab. Wa min sharrin-naffāthāti fil-`uqad. Wa min sharri ḥāsidin idhā ḥasad. Bismillāhir-Raḥmānir-Raḥīm. Qul a`ūdhu birabbin-nās. Malikin-nās. 'Ilāhin-nās. Min sharri ‘l-waswāsil-khannās. Alladhī yuwaswisu fī ṣudūrin-nās. Minal-jinnati wannās. (Surahs 112 al-Ikhlas, 113 al-Falaq, and 114 an-Nas) These Surahs should be recited in Arabic after each prayer. After the Maghrib and Fajr prayers, they should be recited three times each. With the Name of Allah, the Most Gracious, the Most Merciful. Say: He is Allah (the) One. The Self-Sufficient Master, Whom all creatures need, He begets not nor was He begotten, and there is none equal to Him. With the Name of Allah, the Most Gracious, the Most Merciful. Say: I seek refuge with (Allah) the Lord of the daybreak, from the evil of what He has created, and from the evil of the darkening (night) as it comes with its darkness, and from the evil of those who practice witchcraft when they blow in the knots, and from the evil of the envier when he envies. With the Name of Allah, the Most Gracious, the Most Merciful. Say: I seek refuge with (Allah) the Lord of mankind, the King of mankind, the God of mankind, from the evil of the whisperer who withdraws, who whispers in the breasts of mankind, of jinns and men. Reference: Abu Dawud 2/86, An-Nasa'i 3/68. See also Al-Albani, Sahih At-Tirmidhi 2/8.
Allāhu lā ilāha illā huwa ‘l-Ḥayyul-Qayyūm, lā ta'khudhuhu sinatun wa lā nawm, lahu mā fis-samāwāti wa mā fil-ardh, man dhal-ladhī yashfa`u `indahu illā bi'idhnih, ya`lamu mā bayna 'aydīhim wa mā khalfahum, wa lā yuḥītūna bishay'im-min `ilmihi illā bimā shā'a, wasi `a kursiyyuhus-samāwāti wal-ardh, wa lā ya'ūduhu hifẓuhumā, wa huwal-`Aliyyu ‘l-`Aẓīm. Allah! There is none worthy of worship but He, the Ever-Living, the One Who sustains and protects all that exists. Neither slumber nor sleep overtakes Him. To Him belongs whatever is in the heavens and whatever is on the earth. Who is he that can intercede with Him except with His Permission? He knows what happens to them in this world, and what will happen to them in the Hereafter. And they will never compass anything of His Knowledge except that which He wills. His Throne extends over the heavens and the earth, and He feels no fatigue in guarding and preserving them. And He is the Most High, the Most Great. (Recite in Arabic after each prayer.) Reference: An-Nasa'i, 'Amalul-Yawm wal-Laylah (Hadith no. 100), also Ibn As-Sunni (no. 121). See also Al-Albani, Sahihul-Jami' As-Saghir 5/339 and Silsilatul-Ahadith As-Sahihah 2/697 (no. 972).
Lā ilāha illallāh waḥdahu lā sharīka lah, lahu‘l-mulku wa lahu‘l-ḥamd yuḥyī wa yumīt wa huwa `alā kulli shay'in qadīr. (Recite ten times in Arabic after the Maghrib and Fajr prayers.) None has the right to be worshipped but Allah alone, Who has no partner. His is the dominion and His is the praise. He brings life and He causes death, and He is Able to do all things. Reference: At-Tirmidhi 5/515, Ahmad 4/227. See its checking in Ibn Al-Qayyim Al-Jawziyyah's Zddul-Ma'ad 1/300.
Allāhumma innī as'aluka `ilman nāfi`an, wa rizqan ṭayyiban, wa `amalam-mutaqabbala. [to be said after giving salam for the Fajr prayer.] "O Allah, I ask You for knowledge which is beneficial, and sustenance which is good, and deeds which are acceptable." Reference: Ibn Majah and others. See Sahih Ibn Majah 1/152 and Majma' Az-Zawa'id 10/111