Bismillāh.
وَالْبَلَدُ الطَّيِّبُ يَخْرُجُ نَبَاتُهُ بِإِذْنِ رَبِّهِ ۖ وَالَّذِي خَبُثَ لَا يَخْرُجُ إِلَّا نَكِدًا ۚ
The good land—its vegetation comes out by the permission of its Lord, and from the land that is bad, it does not come out except sparsely.
(Sūrat al-A‘rāf No.7, Āyat 58)
The allegory of a good and fertile land versus a land that is barren is used to convey a natural truth. Rain comes down equally on both types of lands, but only the land with the potential for fertility will yield crops. It will absorb the water and allow it to nurture growth that is then manifested externally. The barren land will have water on top of it but does not have the receptivity to absorb it. It is incapable of using the life-giving properties of water. Thus, there is very little vegetation that springs from the water received. The word ‘nakida’ used in the above verse signifies something in which there is no good or benefit. What the barren land produces is of no use to anyone.
The verse could be interpreted as referring to pure families that produce a virtuous progeny. The most obvious manifestation of this is the family of the Ahlul Bayt ‘alayhimus-salām. In Tafsīr Ahlul Bayt, Ali bin Ibrāhīm says, ‘The good land, its vegetation comes out by the permission of its Lord is the example of the Aimmah (a) whose knowledge spreads through His permission, while the unfertile land is the example of their enemies whose knowledge does not produce anything useful (http://alvahy.com).The fertile and barren lands are also interpreted as the various types of hearts that respond differently to the guidance sent by Allah ‘azza wajall. A Hadith of the Prophet sallal-lāhu ‘alayhi wa-ālihi wasallam says: The example of the knowledge and guidance with which Allah sent me is like abundant rain which falls on the earth. (Tafsīr Nūr, under this verse)
Verses of the Quran are like rain that falls from the sky. The soft heart will absorb the verses and react to them. The hard heart is unaffected by the guidance. Many verses of the Quran expound on this reality. Almighty Allah says:
وَنُنَزِّلُ مِنَ الْقُرْآنِ مَا هُوَ شِفَاءٌ وَرَحْمَةٌ لِّلْمُؤْمِنِينَ ۙ وَلَا يَزِيدُ الظَّالِمِينَ إِلَّا خَسَارًا
And We send down of the Quran that which is healing and mercy for the believers, but it does not increase the wrongdoers except in loss (Q 17:82). In another verse He shows how strongly receptive hearts are affected by the verses of Quran.
اللَّهُ نَزَّلَ أَحْسَنَ الْحَدِيثِ كِتَابًا مُّتَشَابِهًا مَّثَانِيَ تَقْشَعِرُّ مِنْهُ جُلُودُ الَّذِينَ يَخْشَوْنَ رَبَّهُمْ ثُمَّ تَلِينُ جُلُودُهُمْ وَقُلُوبُهُمْ إِلَىٰ ذِكْرِ اللَّهِ ۚ
Allah has sent down the best statement: a consistent Book wherein is reiteration. The skins shiver therefrom of those who fear their Lord; then their skins and their hearts relax at the remembrance of Allah (Q 39:23). But those who reject faith will be completely hard and unaffected:
فَوَيْلٌ لِّلْقَاسِيَةِ قُلُوبُهُم مِّن ذِكْرِ اللَّهِ ۚ أُولَٰئِكَ فِي ضَلَالٍ مُّبِينٍ
So, woe to those whose hearts have been hardened to the remembrance of Allah. They are in manifest error (Q 39:22).
The heart is created naturally soft and receptive. It gets hardened due to sins and spiritual diseases. If we find that we are unaffected by Quranic verses, we must examine the state of our hearts. It should not be that it has become like the arid land mentioned in this verse which produces nothing good.
Sources: Āghā Muhsin Qarā’atī, Tafsīr Nūr; https://wiki.ahlolbait.com/