«بِأَصْحَابِ» contains a pronounced hamzat al-qaṭʿ and an emphatic ṣād; do not flatten ṣād into sīn. Its alif after ḥāʾ is an ordinary natural madd.
«رَبُّكَ» has a doubled bāʾ which must be fully articulated without inventing the specialized ghunnah of doubled nūn or mīm.
These are different errors: losing ṣād's heaviness versus shortening a doubled consonant. Assess them separately.
Opening interactive controls...
Bi-aṣḥāb and rabbuka: articulation checks
Al-Fīl and Quraysh: Applied Iẓhār, Ikhfāʾ, Idghām, Madd and Waqf
«بِأَصْحَابِ» contains a pronounced hamzat al-qaṭʿ and an emphatic ṣād; do not flatten ṣād into sīn. Its alif after ḥāʾ is an ordinary natural madd.
«رَبُّكَ» has a doubled bāʾ which must be fully articulated without inventing the specialized ghunnah of doubled nūn or mīm.
These are different errors: losing ṣād's heaviness versus shortening a doubled consonant. Assess them separately.