https://www.tarteelequran.com/qaida/33-page
Lesson No. 13
Rules of Laam
(Page 33)
- The letter Laam of the Name of Allah will be pronounced with heavy sound,with full mouth when it appears after Fatah or Dhammah, and if there is Kasrah before then it will be pronounced slightly with empty mouth.
- The letter Laam except the Laam of the name of Allah will be always pronounced with empty mouth.
- This rule will be implemented in the Laam of Allahumma ,because there is the word Allah.