Musannaf Ibn Abi Shaybah 9954 — One who dies owing itikaf

Ubaydullah bin Abdullah bin Utbah said: My mother had vowed that she would sit in i'tikaf for ten days, but she died and was not able to sit in i'tikaf. Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: "Perform i'tikaf on behalf of your mother."