Asking Allaah for Taqwa and Purification of the Soul

Allahumma, ‘aati nafsee taqwaaha, wa zakkihaa Anta khairu man zakkaahaa, Anta Waliyyuhaa wa Maulaaha'.

O Allah, grant my soul taqwa and purify it, You are the Best of those who purify it, You are its Protecting Friend and Guardian/Master.

Haadith in English:

Zaid bin Arqam reported: I am not going to say anything but only that which Allah's Messenger (may the peace and blessings of Allah be upon him) used to say. He used to supplicate:" O Allah, I seek refuge in Thee from incapacity, from sloth, from cowardice, from miserliness, decrepitude and from torment of the grave. O Allah, grant to my soul the sense of righteousness and purify it, for Thou art the Best Purifier thereof. Thou art the Protecting Friend thereof, and Guardian thereof.(اللَّهُمَّ آتِ نَفْسِي تَقْوَاهَا ، وَزَكِّها أنْتَ خَيْرُ مَنْ زَكَّاهَا ، أنْتَ وَلِيُّهَا وَمَوْلاَهَا )O Allah, I seek refuge in Thee from the knowledge which does not benefit, from the heart that does not entertain the fear (of Allah), from the soul that does not feel contented and the supplication that is not responded."

[Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness {Kitaab ad-dhikr wa duaa wa tawbah wal istighfaar}, Hadith 6568]