The Quran

وَمِنَ النّاسِ مَن يَقولُ آمَنّا بِاللَّهِ فَإِذا أوذِيَ فِي اللَّهِ جَعَلَ فِتنَةَ النّاسِ كَعَذابِ اللَّهِ وَلَئِن جاءَ نَصرٌ مِن رَبِّكَ لَيَقولُنَّ إِنّا كُنّا مَعَكُم ۚ أَوَلَيسَ اللَّهُ بِأَعلَمَ بِما في صُدورِ العالَمينَ

Muhammad Asad

NOW THERE IS among men many a one who says [of himself and of others like him], "We do believe in God" - but whenever he is made to suffer in God's cause, he thinks that persecution at the hands of man is as [much to be feared, or even more than,] God's chastisement;¹ whereas, if succour from thy Sustainer comes [to those who truly believe],² he is sure to say, "Behold, we have always been with you!" Is not God fully aware of what is in the hearts of all creatures?

I.e., the suffering which is bound to befall in the hereafter all who abandon their faith for fear of being persecuted in this world. (It is to be borne in mind that a mere outward renunciation of faith under torture or threat of death is not considered a sin in Islam, although martyrdom for the sake of one's faith is the highest degree of merit to which man can attain.)
I.e., when it is no longer risky to be counted as one of them.