Assalamu 'Alaykum wa Rahmatullahi wa Barakatuh
1. In reciting the verse 77:20 according to Hafs by the way of Shatibi, as I understand, the Qaf can be assimilated (idgham) into the Kaf either partially or completely. I read, however, that in reciting this verse by the way of Tayyibah, only complete assimilation is allowed. Is this correct ? (The pdf document on your website does not mention this)
2. In reciting Hafs by the way of Tayyibah, would the "la" in "La ilaha illallah" be elongated two or four harakat?
3. Are there any principle tajweed differences between the riwayah of Hafs and Shu'bah, or are the differences only in the recitation of particular words?
May Allah accept and increase your efforts.
Wa alaikum assalaam wa rahmatullahi wa barakatuh.
1. The word is read with complete assimilation, or idhgaam kaamil, for all of the different qira’aat including Hafs ‘an ‘Aasim in tareeq Ash-Shatibiyyah and in all of the turuq in Tareeq At-Tayyibah. There are some reports in the old documentations of turuq or ways that have an incomplete assimilation, but none of these ways are mutawaatir and are therefore not read today. Sheikh Muhammed Ad-Dabbaa’ mentioned this in his work on the authentic ways of Hafs, . In the poem written by Sheikh Abdulazeez ‘Uyoon As-Sood which outlines the ways of Hafs ‘an ‘Aasim according to the book there is a line about this. In it, may Allah be merciful to him, he states: , meaning “the merging of nakhluqkum is pure [complete] for Hafs.” There are some modern tajweed books which state that this idhgaam can be read two ways: a. incompletely (with of the ) or b. completely merged into the with no characteristic left over from the . The truth is however, that this is not based on authentic chains of transmission and the assimilation should only be read with a complete merging of the into the .
2. There are 52 turuq or ways of Hafs 'an 'Aasim in Tareeq At-Tayyibah, and there a few of these many ways that allow the lengthening in question. These few ways have two vowel counts for and six vowel counts for and a ghunnah (incomplete merging/assimilation) on the idhgaam of the saakinah and tanween into the and , and have an allowed lengthening for vowel count on the in the phrases declaring that there is no deity except Allah, such as , and . This is called “glorification [magnification] lengthening” or . To read with this lengthening though, one has to follow all the rules for the tareeq and apply them. Please also see an explanation in: http://www.abouttajweed.com/150707.htm .
3. There is no difference in the basic rules, outside of some rules involving words in the and some words having imaalah between Hafs and Shu’bah, other than that and as indicated in the question, the difference is in individual words.
Jazakum Allahu khairan for the dua' and may Allah reward you greatly also.
Wa assalaam alaikum.