لِيَأْكُلُوا مِن ثَمَرِهِ
And We have made therein gardens of date palms and grapes, and We have caused springs of water to gush forth therein. So that they may eat of the fruit thereof --
means, `We have created therein rivers which flow to the places where they are needed, so that they may eat of their fruits.'
When Allah reminds them of the blessing that He bestows upon His creation by creating crops and plants, He mentions the different types and kinds of fruits.
وَمَا عَمِلَتْهُ أَيْدِيهِمْ
and their hands made it not.
means, all of that could only come about by the mercy of Allah towards them, not by their own efforts and labor and strength.
This was the view of Ibn Abbas and Qatadah.
Will they not then give thanks!
meaning, will they not then give thanks for the innumerable blessings that He has bestowed upon them.
Ibn Jarir, however, understood the word Ma to mean Alladhi (i.e., a relative pronoun). In this case the meaning of the Ayah would be that they eat from the fruits provided by Allah's bounty and from what their own hands have done, i.e., by planting the seeds and tending the plants.
Ibn Jarir mentioned other possible interpretations in his Tafsir, but this is the interpretation that he favored. This interpretation also fits with the recitation of Ibn Mas`ud;
لِيَأْكُلُوا مِن ثَمَرِهِ وَمِمَّا عَمِلَتْهُ أَيْدِيهِمْ أَفَلَ يَشْكُرُونَ
(So that they may eat of the fruit thereof -- and from what their own hands have done).
Then Allah says