And here are strong reasons for believing that Paul wrote  HEBREWS  
#1  The  closing  words of this letter are  common to all of  Paul's letters,  GRACE BE WITH YOU ALL . Heb 13:25
#2 , The  mention of  Timothy in Heb  13:23 He was a  co-worker with the  apostle .  Paul considered him as his  son in the  faith , 1  Tim 1:2 , as a deadly beloved son , 2  Tim 1:2
#3 Paul was  instructed IN  all aspects of the  Law  of  Moses , and was  qualified to write to his  brethren after the  flesh , Gal 1:14
#4 Peter said that  Paul had  written a  letter to his people , and it was to be considered as  scripture , 2  Peter 3:15-16  .  If it is not  Hebrews , then where is it ?  If it was  LOST  , THEN teh  Canon of  Scripture is not  complete . Hebrews is that  letter .
# 5 Paul did have a  ministry with  Israel .  Acts 9:15 .  That was part of his commission to him by the  ASCENDED  Christ .  Hebrews belongs to this part ofnhis  minstry , and  accounts for why the  GREEK  is  different from his letters to  Gentile  churches .
#6 Paul is the  only writer to  quote Habakkuk 2:4 in the  new  testament 3  times , each with  different  emphasis  , Rom 1:17  ,  Gal 3:11  and  Heb 10:38 .
#7 Paul is the only  apostle to ask for  prayer for himself , Heb 13:18 -- pray for us .
8  Paul is the  ONLY  witer in the  New  Testament who wrote about the  PASSING  away of thr  Law  of  Moses , the  Old  Covenant , Heb  8:13in line with what He  wrote in 2  Cor 3:10--18  ,  Eph 2:15  anf Col  2:14 .
#1  ,Does  the  writing of  Hebrews contradict the  MANY  revelations that Paul recieved from the  risen Christ  concerning the  MYSTERY  and the  BODY of  Christ ??  NO  , it  doesn't because he  wrote to  Hebrews If  Pal has  written this letter to  Gentiles or to the  BODY  of  CHRIST  , then  HEBREWS wopuld be  contradictory in  nature .
#2 In  believing that Paul wrote  Hebrews , does this  belief make  VOID  his  commission to the  GENTILES  as  stated in  Acts  9:15 ??No  , of course  not  !
In  fact it  tends to enhance it  because his  commission was  TWOFOLD ;
#1 To  Gentiles  and  Kings
#2 , To the  children of  Israel   ,  NOT  the  NATION  of  ISRAEL  .
All of this is from Robert  C  Brock  as he  wrote a  booklet  of  227  pages and have left out , more of this  words
dan p