Is one who does not write down a debt sinful, especially if the debtor is a relative, given the command to write down a debt in verses 282 and 283 of Surat Al-Baqarah?

Writing down a debt and having a sale witnessed are considered recommended, not obligatory, due to the Almighty’s saying: (But if one of you entrusts another, then let him who is entrusted discharge his trust and let him fear Allah, his Lord). So, the command for them is for guidance, not for obligation, and this is the view of the majority of jurists.