"It gives its fruit" - meaning its produce - "every season by the permission of its Lord," meaning: by His command. Al-Hasan's interpretation is: He says that the believer continues to produce good speech and righteous deeds, just as this tree yields its fruit at every season.
Yahya said: "The 'hin' (season/time) in the interpretation of some of them is: a year, and it is consumed in both winter and summer.
Muhammad said: "The 'hin' in the language is: a noun for a time among the times of duration; it is used for both long and short periods."
﴿تؤتي أكلهَا﴾ ثَمَرَتَهَا ﴿كُلَّ حِينٍ بِإِذْنِ رَبِّهَا﴾ أَيْ: بِأَمْرِهِ. تَفْسِيرُ الْحَسَنِ: يَقُولُ: إِنَّ الْمُؤْمِنَ لَا يَزَالُ مِنْهُ كلامٌ طيبٌ وعملٌ صالحٌ؛ كَمَا تُؤْتِي هَذِهِ الشَّجْرَةُ أُكُلَهَا فِي كُلِّ حِينٍ.
قَالَ يحيى: (وَالْحِينُ) فِي تَفْسِيرِ بَعْضِهِمْ: السَّنَةُ، وَهِيَ تُؤْكَلُ شِتَاءً وَصَيْفًا.
قَالَ محمدٌ: (الْحِينُ) فِي اللُّغَةِ: اسْمُ وقتٍ مِنْ أَوْقَاتِ الزَّمَانِ يُسْتَعْمَلُ فِيمَا طَال وَقصر.