allah the almighty says {o you who have believed why do you say that which you do not do? great is hatred in the sight of allah that you say that which you do not do} . and the messenger of allah may allah bless him and grant him peace was asked can a believer be stingy? he said yes. it was said can a believer be a coward? he said yes. it was said can a believer be a liar? he said no. ahmad ibn muhammad ibn ahmad narrated to us from ahmad ibn saeed from ubaydullah ibn yahya from his father from malik ibn anas from safwan ibn sulaym. and with this chain of transmission the messenger of allah may allah bless him and grant him peace said there is no good in lying in a hadith in which he was asked. and with this chain of transmission from malik that it reached him from ibn masoud that he used to say a servant will continue to lie and black dots will be placed in his heart until the heart turns black and he will be recorded with allah as one of the liars. and with this chain of transmission from ibn masoud may allah be pleased with him that he said you must be truthful for it leads to righteousness and righteousness.
والله عز وجل يقول {يا أيها الذين آمنوا لم تقولون ما لا تفعلون. كبر مقتا عند الله ان تقولوا ما لا تفعلون} . وعن رسول الله صلى الله عليه وسلم أنه سئل هل يكون المؤمن بخيلا فقال نعم. قيل فهل يكون المؤمن جبانا فقال نعم. قيل فهل يكون المؤمن كذابا فقال لا. حدثناه أحمد بن محمد ابن احمد عن أحمد بن سعيد عن عبيد الله بن يحيى عن أبيه عن مالك بن أنس عن صفوان بن سليم. وبهذا الإسناد، أن رسول الله صلى الله عليه وسلم قال لا خير في الكذب في حديث سئل فيه. وبهذا الإسناد عن مالك أنه بلغه عن ابن مسعود أنه كان يقول لا يزال العبد يكذب وينكت في قلبه نكته سوداء حتى يسود القلب فيكتب عند الله من الكذابين وبهذا الإسناد عن ابن مسعود رضي الله عنه أنه قال عليكم بالصدق فإنه يهدي إلى البر والبر