Al-Kāfi - Volume 6 > Clipping or Pulling out Gray Hairs
Hadith #4

وَ بِهَذَا الْإِسْنَادِ قَالَ ( عليه السلام ) أَوَّلُ مَنْ شَابَ إِبْرَاهِيمُ ( عليه السلام ) فَقَالَ يَا رَبِّ مَا هَذَا فَقَالَ نُورٌ وَ تَوْقِيرٌ قَالَ رَبِّ زِدْنِي مِنْهُ .

4. Through the same chain of narrators as that of the previous Hadith the following is narrated: “He (the Imam), ‘Alayhi al-Salam, has said, ‘The first one who noticed gray hairs was Ibrahim ‘Alayhi al-Salam, and he asked, ‘O Lord, what is this?’ He said, ‘It is light and reverence.’ He then said, ‘O Lord, increase it for me.’”