How can one reconcile the dispraise in the first Hadith for those who testify without being asked, with the praise in the second Hadith for those who offer their testimony before being asked? What is the meaning of "fatness appearing in them"? And what is meant by Ibrahim al-Nakha'i's saying: "They used to beat us for bearing witness and for covenants when we were young"?

There is no contradiction between the Hadiths regarding "testimony" (Shahada) and "fatness" (Saman). They are reconciled by understanding that the dispraise of testimony is for one who bears false witness, or who testifies before being asked, knowing that the rights belong to another. As for its praise, it is for one who testifies truthfully for a benefit unknown to the right-holder. The dispraise of fatness is for one who excessively indulges in luxury and eating to improve their physique, and not for one who became fat unintentionally. As for striking an oath on "testimony and covenant," it is a disciplinary measure to prevent excessive swearing by Allah.