Sahih Muslim Book 10, Hadith Number 3671.

Chapter : Prohibition of the sale of fruits until they are clearly in good condition.

Ibn Umar (Allah be pleased with them) reported Allah’s Messenger'(may peace be upon him) as saying: Do not buy fruits (on the trees) until their good condition becomes clear. In the hadith transmitted on the authority of Shu’ba it was stated that Ibn Umar (Allah be pleased with them) was asked what good condition implied. He said: When (the danger of) blight is no more.