Mukhtasar Bukhari (Abridged) 2086 — Virtue of saying “La ilaha

It is narrated from Sayyiduna Abu Ayyub Ansari and Ibn Mas'ud (may Allah be pleased with them) that the Prophet Muhammad (peace and blessings be upon him) said: "Whoever recites the above-mentioned phrase (the declaration of faith: La ilaha illallah...) ten times, will receive a reward as if he has freed one slave from the descendants of Isma'il (peace be upon him)."