WE RELATE FROM the book of Ibn as-Sunnī that Umm Rafī‘ 
said: “Messenger of Allah, show me a deed for which Allah 
will reward me.” He said: “Umm Rafī‘, when you stand up for ṣalāh glorify Allah ten times, say There is no god but Allah ten times, praise Him ten times, say Allah is greater ten times, and ask His forgiveness ten times. For when you glorify Allah He says: ‘This is for Me.’ When you say There is no god but Allah He says: ‘This is for Me.’ And when you praise Allah He says: ‘This is for Me.’ When you say Allah is greater He says: ‘This is for Me.’ And when you ask Him to forgive you He says: ‘I have done so.’” [1].
said: “Messenger of Allah, show me a deed for which Allah will reward me.” He said: “Umm Rafī‘, when you stand up for ṣalāh glorify Allah ten times, say There is no god but Allah ten times, praise Him ten times, say Allah is greater ten times, and ask His forgiveness ten times. For when you glorify Allah He says: ‘This is for Me.’ When you say There is no god but Allah He says: ‘This is for Me.’ And when you praise Allah He says: ‘This is for Me.’ When you say Allah is greater He says: ‘This is for Me.’ And when you ask Him to forgive you He says: ‘I have done so.’” [1].References
[1] Ibn as-Sunnī (105) and al-Futūḥāt (2/144). Ib.n Ḥajar grades it as ḥasan.