The Weekly Shtikle is dedicated le'iluy nishmas my Oma, Chaya Sara bas Zecharia Chaim, a"h.

When Avraham and Sarah, then Avram and Sarai, come to Mitzrayim, Avraham asks her to tell the Mitzri’im that she is his sister "l'ma'an yitav li ba'avureich, v'chaysa nafshi biglaleich" (12:13), so that they will do good to me and I will live because of you. Rashi comments on "l'ma'an yitav li," that they will give him presents. The obvious question that many ask is why Avraham seems to be so interested in gifts. We know from later in the parsha that Avraham was not one to desire gifts in the least. Why is this different? Another question to be asked is why the receiving of presents is put before survival? Surely receiving presents was not more important than coming out alive.

The Ta"Z, in his sefer on Rashi, Divrei David, answers the first question beautifully. When they came down to Mitzrayim, they had a dilemma. Surely, they did not want the Egyptians to think they were married. That would be the worst-case scenario. But for them to come into Mitzrayim and for Sarah to blurt out, unprovoked, "he's my brother," would also have seemed very suspicious. But if they never asked, and she never told, they ran the risk of the assumption that they were indeed husband and wife. So, they needed a plan to tell them that they were brother and sister with a pretense. This was their plan: Sarah would come to Mitzrayim with Avraham and say "This is my brother, a very poor man. Please give him some money." By doing this, there is a very legitimate reason for her to say that he is her brother. This would invoke a feeling of pity and the Mitzri'im would be likely to give gifts. If she had just come in with any beggar off the street, they might not be inclined to give him. With this crafty plan, they have informed the Mitzri'im that they are brother and sister without looking suspicious. And the Mitzri'im will give gifts to Avraham because of Sarah.

This answer may be used to alleviate the second difficulty as well. Only "v'chaysa nafshi..." is really what Avraham wanted to get out of the whole deal. The phrase "l'ma'an yitav li" is not as much a statement of what Avraham wanted, but more of what he wanted Sarah to say, that they should give her brother presents as the Ta"Z explains.

I propose another suggestion, though, exclusive of the Ta"Z's explanation. The two results of the situation are not put in order of what was important to Avraham, but more of an order of events from the Mitzri'im's perspective. If they were husband and wife, surely, they would know they have no chance with Sarah and they would kill Avraham right away. But now that they are brother and sister, they will simply give Avraham gifts to convince them to let them have Sarah. But if this does not convince him, then they will still have to kill him. So, the Mitzri'im had the mindset, "If he accepts the gifts, we will let him live." That is why the order in the pasuk is "they will give me gifts, and they will let me live" because it is the accepting of the gifts on which his survival relies.

Have a good Shabbos.