Surah Al A'raf Tafseer

Allah says,

مَن يَهْدِ اللّهُ فَهُوَ الْمُهْتَدِي

وَمَن يُضْلِلْ فَأُوْلَـيِكَ هُمُ الْخَاسِرُونَ

Whomsoever Allah guides, he is the guided one, and whomsoever He sends astray, -- then those! They are the losers

Allah says, whomever He leads aright, then none can lead him to misguidance, and whomever He leads astray, will have acquired failure, loss and sure misguidance. Verily, whatever Allah wills occurs; and whatever He does not will, does not occur.

A Hadith narrated from Abdullah bin Mas`ud reads,

إِنَّ الْحَمْدَ للهِ نَحْمَدُهُ وَنَسْتَعِينُهُ وَنَسْتَهْدِيهِ وَنَسْتَغْفِرُهُ وَنَعُوذُ بِاللهِ مِنْ شُرُورِ أَنْفُسِنَا وَمِنْ سَيِّيَاتِ أَعْمَالِنَا مَنْ يَهْدِ اللهُ فَلَ مُضِلَّ لَهُ وَمَنْ يُضْلِلِ اللهُ فَلَ هَادِيَ لَهُ وَأَشْهَدُ أَنْ لَا إِلَهَ إِلاَّ اللهُ وَحْدَهُ لَا شَرِيكَ لَهُ وَأَشْهَدُ أَنَّ مُحَمَّدًا عَبْدُهُ وَرَسُولُه

All praise is due to Allah, Whom we praise and seek help, guidance and forgiveness from. We seek refuge with Allah from the evils within ourselves and from the burden of our evil deeds. He whom Allah guides, will never be misled; and he whom He misguides, will never have one who will guide him. I bear witness that there is no deity worthy of worship except Allah without partners and that Muhammad is His servant and Messenger.

The complete Hadith was collected by Imam Ahmad and the collectors of Sunan and others