Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Whoever, after performing the morning prayer, recites this ten times: 'La ilaha illallahu wahdahu la sharika lah, lahu al-mulku wa lahu al-hamdu, wa huwa 'ala kulli shay'in qadir'
(There is no god except Allah Almighty, He alone is the only one worthy of worship, He has no partner; the dominion belongs to Him alone, and praise belongs to Him alone, and He has power over all things),
(the Prophet (peace and blessings be upon him) says:) then this deed will be equal for him to freeing four slaves; because of these words ten good deeds will be recorded for him, and because of these words ten of his sins will be erased, and these words will become a means of protection for him from Satan until the evening; and if a person recites them after Maghrib, he will receive the like of it (that is, the same reward)."
Ahmad recorded it, and al-Tabarani recorded it in abridged form; Ahmad's chain contains Muhammad bin Ishaq, and he is a mudallis, while al-Tabarani's narration contains Muhammad bin Abi Layla, who is thiqah (trustworthy) but suffers from poor memory; the narrators of both are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأذكار / 16955