Such a strange story – like a ghost story. Abram must have felt a sense of awe, almost dread, and felt himself to be quite small and insignificant – except that this awesome God gives him a worldwide significance! A useful corrective to any tendency we may have to be too “pally” with God.
I found this link helpful for more explanation -Abraham asks questions of God -heir & land & God makes a covenant with Abraham. Amazing faith by Abraham after God replies to his questions. In another link it also mentioned the birds that Abraham did not cut in half and apparently this was an error and the birds of prey that swooped to seize them represent evil – the fact that Abraham did not cut the birds in half was an error and shows that we need to take care of the small things in our life as well as big. The weblink suggested that Gods enslavement of Abraham’s descendants was die to this error?