I learnt in my tajweed class that if u pause on the word minhu it becomes minh. 2 sakins cannot come together in the arabic language.

Question
assalamalaikum
I learnt in my tajweed class that if u pause on the word minhu it becomes minh.2 sakins cannot come together in the arabic language.therefore a fatha with one fourth of the timing should be given to noon, just enough to make it bounce like a qalqalah word, so the word would now sound like minah.similarly with the words of surah fajar like watr will be watar and ashr will be ashar etc. But i listened to at least 8 qaris and nobody was doing it. please enlighten me on this.

Answer
Wa alaikum assalaam wa rahmatullahi wa barakaatuh
The prohibition of two saakin letters meeting in the Arabic language is between two words, not within one word.  When two saakin letters meet within one word, it occurs when we are stopping on a word with a incidental sukoon on the last letter and it is preceded by a letter with a sukoon, such as in: .  When this happens the reciter needs to pronounce the saakin letter correctly with all of its characteristics, and no vowel whatsoever, then go on to pronounce the next letter with a sukoon. 
There is no addition of a vowel or partial vowel on the first of the two saakin letters in a case like this and no rule of recitation which states that this should happen in the case of two saakin letters meeting within a word.