The source cites «رَحْمٰن» as a form whose Qurʾānic spelling differs from ordinary orthography in the writing of alif. Its recited long vowel remains; absence of a normally written full alif is not permission to shorten the word.
In «الرَّحْمَٰنِ الرَّحِيمِ», preserve the established vowel length. A written omission is not automatically a spoken omission.
Opening interactive controls...
Al-Raḥmān: a written alif may be absent
Conclusion: Tajwīd, Waqf, ʿUthmānic Rasm and Qirāʾāt
The source cites «رَحْمٰن» as a form whose Qurʾānic spelling differs from ordinary orthography in the writing of alif. Its recited long vowel remains; absence of a normally written full alif is not permission to shorten the word.
In «الرَّحْمَٰنِ الرَّحِيمِ», preserve the established vowel length. A written omission is not automatically a spoken omission.