It is narrated from Ikrimah bin Khalid that Sa'd said to his son at the time of his death: "O my son! You will never find anyone more sincere in advising you than me. When you intend to pray, perform ablution well, then pray a prayer as though you are certain that you will not pray again after it. Beware of greed, for it is poverty at hand, and adopt independence (from what people have), for that is true wealth. And beware of any deed or word for which you would later have to apologise, and do whatever you wish."
Hadith Referenceالمعجم الكبير للطبراني / العشرة / 310