For when they came into the house, he lay on his bed in his
 bedchamber
 This is repeated to give a more particular account of the murder; though Abarbinel thinks they went in twice; when they went in first they smote him under the fifth rib, and made their escape; but fearing they had not left him dead, they returned, and did as follows: 
 and they smote him, and slew him;
 so that it was out of all doubt with them that he was dead: 
 and beheaded him;
 to make sure work of it: 
 and took his head;
 along with them, perhaps in one of the sacks they had to fetch wheat in, and so passed undiscovered, to carry to David, to curry favour with him: 
 and gat them away through the plain all night;
 through the plain of Jordan; all the way from Mahanaim to Hebron being for the most part a plain country till they came to Hebron, which was mountainous; the way from Mahanaim to Hebron was a space of sixty eight miles, according to Bunting F26.