Lech Lecha 5778

The Ramban points out in two places where both Avraham and Sarah both erred in their actions. At the beginning of the parsha, Avraham leaves Israel in order to find food in Egypt during the famine. The Ramban mentions that he did two things wrong. One was that he put his wife in a dangerous situation; by saying Sarah is his sister, that would only entice others to take her even more. The other was leaving in the first place; Avraham had shown a lack of faith in G-d and His being able to provide food for him. Because of this, his descendants would also leave Israel for Egypt only to be enslaved for hundreds of years.
Sarah also erred in her treatment of Hagar. As tension grew in the household, Sarah began mistreating Hagar to the point of Hagar running away. The Ramban says she did a grievous sin doing so. Because of this, Hagar's descendants would be destined to mistreat and be harsh with Sarah's descendants to this very day.
The Torah points out the mistakes of the patriarchs and matriarchs to teach us proper conduct. It also shows us that they were human despite their holy status. This allows us to strive to reach their level without thinking of it as an impossible feat.