Whoever says ten times

The Prophet (may Allah's peace and blessings be upon him) informs about the dhikr that says: "Lā ilāha illa Allah wahdahu lā sharīka lahu, lahu al-mulku wa lahu al-hamdu, wa huwa ‘ala kulli shay’in qadīr (There is no god but Allah, alone, with no partner; to Him belongs the dominion, and praise is due to Him, and He has power over all things)", and it means: None is worthy of worship except Allah, alone, with no partner, and that He is the Possessor of the whole dominion and the One worthy of praise along with love and extolment, apart from all else; and that He is Powerful and nothing escapes His power. Whoever repeats this dhikr ten times during a day will have a reward similar to the reward for manumitting four slaves from the children of Ishmael, the son of Abraham (peace be upon both of them). He singled out the children of Ishmael because they are nobler than others.