What is said about planting trees

Narrated Sahl bin Sa`d: We used to be very happy on Friday as an old lady used to cut some roots of the Silq, which we used to plant on the banks of our small water streams, and cook them in a pot of her's, adding to them, some grains of barley. (Ya'qub, the sub-narrator said, "I think the narrator mentioned that the food did not contain fat or melted fat (taken from meat).") When we offered the Friday prayer we would go to her and she would serve us with the dish. So, we used to be happy on Fridays because of that. We used not to take our meals or the midday nap except after the Jumua prayer (i.e. Friday prayer).