We were on a journey, and Ibn Umar was with us. I asked him about voluntary prayer during travel, and he said, "I saw the Messenger of Allah ﷺ not perform any voluntary prayer during travel, neither before the obligatory prayer nor after it."He continued, "I also asked Ibn Umar about selling fruits, and he said, 'The Messenger of Allah ﷺ forbade selling fruits until the blight has passed.'"I asked, "Abu Abdul-Rahman, when does the blight pass? What is the blight?"He replied, "The rising of the Pleiades."
حدثنا يزيد بن هارون قال أخبرني ابن أبي ذئب
كنا في سفر ومعنا ابن عمر فسألته فقال رأيت رسول الله ﷺ لا يسبح في السفر قبل الصلاة ولا بعدها قال وسألت ابن عمر عن بيع الثمار فقال نهى رسول الله ﷺ عن بيع الثمار حتى تذهب العاهة قلت أبا عبد الرحمن وما تذهب العاهة ما العاهة قال طلوع الثريا
Its isnad is sahih. In reality it is two hadiths, the first about voluntary prayer while traveling, something similar to which has already appeared as 4765 from the hadith of Ibn Abu Dhib from Uthman bin Abdullah bin Suraqa. Its meaning has also already appeared with an unspecified isnad as 4962, by way of Ubaydullah from someone who heard Ibn Suraqa, and it has already appeared by another sahih route as 4761. See also 5634.The second is the prohibition against selling fruit before it is free of blight, the meaning of which has already appeared several times, most recently as 4943 and 4998. Regarding "blight," Ibn Athir said, it means the defect that afflicts fruit and spoils it. It is said, "the people were struck by blight," when blight afflicts their fruits and livestock. As for Ibn Umar's explanation of "blight" as the rising of the Pleiades, he means by this the time when blight ceases to affect fruit in their reckoning. So this is a definition of the timing, not an explanation of the word itself.