In Surah Maryam the rhyming pattern is very distinct and consistent throughout the beginning of the Surah all the way up until the point that it begins to address Isa (alayhis Salam).
Listen to [or read] Surah Maryam [surah/chapter 19], starting from verse [19:]2, all the way to verse 33. This is a narrative of the story of Prophet Zakariyyah, and Maryam/Mary (peace be upon them.) Then it begins briefly on the birth of Prophet ‘Eesa/Jesus.
So at the end of every aayah/verse, there is an “iyya” sound at the end. I.e. زَكَرِيَّا [Zakariyyah] (in the 2nd verse), with شَقِيًّا [Shakkiyya] (on the 32nd verse), حَيًّاHayya [meaning 'Life'] (on the 33rd verse). With the 33rd verse referring to Jesus talking whilst being a baby.
Suddenly, a Drastic change takes place – the Rhyming Scheme changes totally:
ذَٰلِكَ عِيسَى ابْنُ مَرْيَمَ ۚ قَوْلَ الْحَقِّ الَّذِي فِيهِ يَمْتَرُونَ
That is Jesus, the son of Mary – the word of truth about which they are in dispute. [Maryam 19:34]
The last word now is ‘yamtaroon‘.
Why is this rhyming scheme changed?
Part of the characteristics of the Quran is that it is something meant to be recited and heard by the people. When someone is listening to this, and they notice an abrupt change they willautomatically pay more attention. The rhyme scheme is not beautification only, but it serves a very real purpose in drawing attention to a very important point in the Surah.
This important point in the Surah is clearing the doubts on the character Jesus son of Mary, about whom they are in dispute. This abrupt change makes you notice a difference in rhythm and tune, it must be really big news for the tune/rhythm/theme to change totally after so long.. It gives focus, and clears the doubts of the sincere listener.
After that part is finished, Allah starts talking about Ibrahim/Abraham (alayhis Salam) and his story [from Surah Maryam 19:34 onwards], it returns back to the original pattern (with ‘Iyya‘ at the end of the verses again).. To continue the flow of what was being mentioned previously of the narratives of the righteous.