Yuthabbitu Allahu allatheena amanoo bilqawli aththabiti fee alhayati addunya wafee al-akhirati wayudillu (surah Ibrahim: 27)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(14:27) Allah makes the believers steadfast in the life of this world and of the Hereafter with the firm Word *39 but lets the transgressors go astray. *40 Allah has full power to do as He will.

Yusabbitul laahul lazeena aamanoo bilqawlis saabiti fil hayaatid dunyaa wa fil Aakhirati wa yudillul laahuz zaalimeen; wa yaf`alul laahu maa yashaaa

*39) That is, "The believers remain steadfast during the life of this world because of their stable system of life based on this "Pure Word" For this gives than a straight point of view, a sound system of thought and a comprehensive theory of life, and it serves as a master key to the unravelling of aII knots and the solving of all problems. With its help, they acquire that strength of character and that firmness of conduct which keep them steady in the face of every vicissitude of life. This provides them also with such solid principles of life which give them peace of mind and heart, and prevent them from deviation and caprice. Above all, when, after the life of this world, they will enter into the life of the Hereafter, they will remain perfectly calm without any tinge of fear or anxiety, for they will find everything therein to be in accordance with their expectations, as if they were fully acquainted with every aspect of it before they entered into it. For they had been .fully informed of, and therefore fully prepared for every stage and phase of this life. That is why they will pass through every stage with perfect calmness and firmness in contrast to the disbelievers who built their worldly lives on an "evil word" and will, therefore, be taken aback to find everything against their expectations.
*40) That is, "AIIah lets the transgressors, who discard the "Pure Word" and follow an "evil word", go astray by creating confusion in their minds and misdirecting their efforts because of this deviation. That is why they cannot find the right way of thought and action and so fail miserably.