It is narrated from Imam Ridha/Reza (AS) who said:

Prayers (to God) is a good thing (deed), the place of Wajib Salaat and fasting is protected. The rewards for Mostahab Salaats are also reserved; but these are not (real) worshipping. Worship (of God) is not just performing a lot of Salaat and fasting; rather (true/real) worship is to think a lot about God [1]. Think and reflect on Divine Management, live life as believers (having full belief in Allah (SWT) and utilize God’s commands in every aspect of life); this is (true) worship of God [2].

[1] Tohaful Oqool, Page 442.

[2] Part of speech by the Grand Ayatollah Javadi Amoli, (26/07/2018).

Source: en.shafaqna.com