Nahjul Balagha Part 2, Letters and Sayings
Letter 72: To Abdullah ibn al-Abbas
ومن كتاب له (عليه السلام)
إلى عبدالله بن العباس
Now, you cannot go farther than the limit of your life, nor can you be given a livelihood which is not for you. Remember that this life consists of two days - a day for you and a day against you, and that the world is a house (changing) authorities. Whatever in it is for you will come to you despite your weakness; and whatever in it turns against you cannot be brought back despite your strength.
أَمَّا بَعْدُ، فَإِنَّكَ لَسْتَ بِسَابِق أَجَلَكَ، وَلاَ مَرْزوُق مَا لَيْسَ لَكَ. وَاعْلَمْ بِأنَّ الدَّهْرَ يَوْمَانِ: يَوْمٌ لَكَ وَيَوْمٌ عَلَيْكَ، وَأَنَّ الدُّنْيَا دَارُ دُوَل، فَمَا كَانَ مِنْهَا لَكَ أَتَاكَ عَلَى ضَعْفِكَ، وَمَا كَانَ مِنْهَا عَلَيْكَ لَمْ تَدْفَعْهُ بقُوَّتِكَ.