Hebrews 12:25-29. Chiastic structure copied from Chiastic Analysis of the Epistle to the Hebrews,  arranged by John Bligh (Athenaeum Press, Heythrop College, Oxon, England: 1966). Bligh's work is almost entirely in Greek. For website purposes, I have used unaccented Greek from the Unbound Bible, Nestle-Aland 26, at unbound.biola.edu
I have added English from the New American Standard Bible, revised.

A 25 blepete mh paraithshsqe ton lalounta 
See to it that you do not refuse Him who is speaking. 
B ei gar ekeinoi ouk exefugon 
For if those did not escape 

epi ghV paraithsamenoi ton crhmatizonta 
when they refused him who warned them on earth, 

C polu mallon hmeiV oi ton ap ouranwn apostrefomenoi
much less will we escape who turn away from Him who warns from heaven.
D 26 ou h fwnh thn ghn esaleusen tote
And His voice shook the earth then, 
E nun de ephggeltai legwn eti apax egw seisw 
but now He has promised, saying, "Yet once more I will shake
F ou monon thn ghn alla kai ton ouranon
 not only the earth, but also the heaven."
G 27 to de eti apax dhloi [thn] twn saleuomenwn metaqesin 
This expression, "Yet once more," denotes the removing of those things which can be shaken, 
F* wV pepoihmenwn 
as of created things, 
E* ina meinh ta mh saleuomena
so that those things which cannot be shaken may remain.
D* 28 dio basileian asaleuton 
Therefore, since ... a kingdom which cannot be shaken, 
C* paralambanonteV ecwmen carin 
we receive ...let us show gratitude, 
B* di hV latreuwmen euarestwV tw qew meta eulabeiaV kai deouV
by which we may offer to God an acceptable service with reverence and awe;
A* 29 kai gar o qeoV hmwn pur katanaliskon
for our God is a consuming fire.

Verse 29 is also in the next chiasm.