It is narrated from Aslam (may Allah have mercy on him) that Sayyiduna Umar (may Allah be pleased with him) said to me: When I send you to someone to call him, do not tell him why I have called him, because in this way Satan will prepare a lie for him (regarding this matter) and he will not tell the truth.
Hadith Referenceالادب المفرد / كتاب / 1156
Hadith Gradingالألبانی:ضعيف الإسناد موقوفًا
Hadith Takhrij«ضعيف الإسناد موقوفًا : أخرجه ابن وهب فى الجامع : 62 و ابن شبة فى تاريخ المدينة : 752/2»