Hebrews 6:13-20. 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 13 tw gar abraam epaggeilamenoV o qeoV 
For when God made the promise to Abraham, 

epei kat oudenoV eicen meizonoV omosai wmosen kaq eautou
since He could swear by no one greater, He swore by Himself,

14 legwn ei mhn eulogwn euloghsw se kai plhqunwn plhqunw se
saying, "I will surely bless you and I will surely multiply you."
B 15 kai outwV makroqumhsaV epetucen thV epaggeliaV
And so, having patiently waited, he obtained the promise.
C 16 anqrwpoi gar kata tou meizonoV omnuousin 
For men swear by one greater than themselves, 

kai pashV autoiV antilogiaV peraV eiV bebaiwsin o orkoV
and with them an oath given as confirmation is an end of every dispute.
D 17 en w perissoteron boulomenoV o qeoV epideixai 
In the same way God, desiring even more to show 

toiV klhronomoiV thV epaggeliaV to ametaqeton thV boulhV autou 
to the heirs of the promise the unchangeableness of His purpose, 
E emesiteusen orkw   interposed with an oath,
D* 18 ina dia duo pragmatwn ametaqetwn 
so that by two unchangeable things 
C* en oiV adunaton yeusasqai [ton] qeon 
in which it is impossible for God to lie, 

iscuran paraklhsin ecwmen 
we ...would have strong encouragement 
B* oi katafugonteV krathsai thV prokeimenhV elpidoV
who have taken refuge... to take hold of the hope set before us.
A* 19 hn wV agkuran ecomen thV yuchV  This hope we have as an anchor of the soul, 

asfalh te kai bebaian kai eisercomenhn eiV to eswteron tou katapetasmatoV
a hope both sure and steadfast and one which enters within the veil,

20 opou prodromoV uper hmwn eishlqen ihsouV 
where Jesus has entered as a forerunner for us, 

kata thn taxin melcisedek arciereuV genomenoV eiV ton aiwna
having become a high priest forever according to the order of Melchizedek.