Hudhaifa reported: We were sitting with Umar ibn Al-Khatab and he said, “Who among you has heard the Messenger of Allah mention tribulation?” Some people said, “We have heard it.” Umar said, “Perhaps it is the unrest a man might experience with his household and neighbor.” They said yes. Umar said, “Such unrest will disappear with prayer, fasting, and charity. Rather, who has heard mention from the Prophet describing a tribulation like the waves of the ocean?” The people were silent and I said I have heard it. Umar said, “You and your father are good men for Allah.” I said I heard the Messenger of Allah, peace and blessings be upon him, say, “Tribulation will be presented to the hearts of people like a reed mat woven stick by stick and any heart afflicted by them will have a black mark put into it, but any heart that rejects them will have a white mark put into it. Thus there will be two kinds of hearts: one is pure like a white gemstone and it will not be harmed by any tribulation as long as the heavens and earth endure, and the other is black and dusty like a worn-out vessel, neither recognizing good nor rejecting evil, but rather immersed in its desires.”

Source: Sahih Muslim 144

Grade: Sahih (authentic) according to Muslim

عَنْ حُذَيْفَةَ قَالَ كُنَّا عِنْدَ عُمَرَ فَقَالَ أَيُّكُمْ سَمِعَ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَذْكُرُ الْفِتَنَ فَقَالَ قَوْمٌ نَحْنُ سَمِعْنَاهُ فَقَالَ لَعَلَّكُمْ تَعْنُونَ فِتْنَةَ الرَّجُلِ فِي أَهْلِهِ وَجَارِهِ قَالُوا أَجَلْ قَالَ تِلْكَ تُكَفِّرُهَا الصَّلَاةُ وَالصِّيَامُ وَالصَّدَقَةُ وَلَكِنْ أَيُّكُمْ سَمِعَ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَذْكُرُ الْفِتَنَ الَّتِي تَمُوجُ مَوْجَ الْبَحْرِ قَالَ حُذَيْفَةُ فَأَسْكَتَ الْقَوْمُ فَقُلْتُ أَنَا قَالَ أَنْتَ لِلَّهِ أَبُوكَ قَالَ حُذَيْفَةُ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ تُعْرَضُ الْفِتَنُ عَلَى الْقُلُوبِ كَالْحَصِيرِ عُودًا عُودًا فَأَيُّ قَلْبٍ أُشْرِبَهَا نُكِتَ فِيهِ نُكْتَةٌ سَوْدَاءُ وَأَيُّ قَلْبٍ أَنْكَرَهَا نُكِتَ فِيهِ نُكْتَةٌ بَيْضَاءُ حَتَّى تَصِيرَ عَلَى قَلْبَيْنِ عَلَى أَبْيَضَ مِثْلِ الصَّفَا فَلَا تَضُرُّهُ فِتْنَةٌ مَا دَامَتْ السَّمَاوَاتُ وَالْأَرْضُ وَالْآخَرُ أَسْوَدُ مُرْبَادًّا كَالْكُوزِ مُجَخِّيًا لَا يَعْرِفُ مَعْرُوفًا وَلَا يُنْكِرُ مُنْكَرًا إِلَّا مَا أُشْرِبَ مِنْ هَوَاهُ

144 صحيح مسلم كِتَاب الْإِيمَانِ باب بَيَانِ أَنَّ الْإِسْلَامَ بَدَأَ غَرِيبًا وَسَيَعُودُ غَرِيبًا وَأَنَّهُ يَأْرِزُ بَيْنَ الْمَسْجِدَيْنِ

Author of page says about reed mat woven stick by stick

"As-Salaamu Alaykum, it means the trials will come like layers or in a sequence, one after the other. The people will be put to trial on one issue and shortly thereafter another different trial will come. We should seek refuge in Allah as the Prophet (SAW) warns us that these trials will corrupt our hearts if our faith is weak. Allah knows best."