The Torah tells us that if your brother becomes poor “with you” you should strengthen him so that he can live “with you.” But why does the Torah say "עמך" (“with you”) twice? It seems to be redundant. Also, why does the Torah say "והחזקת בו" (literally “strengthen in him”); wouldn’t the correct grammar be "והחזקת אותו" (“strengthen him”)? 

     R' Chaim Yosef Kofman zt"l (Machsheves HaLev) explains that people do not always know what is going on by “yenem” - another person’s personal issues. Sometimes, a poor man will approach someone who is known as a rich man and ask him for money. What he doesn’t know is that the rich man is also experiencing financial hardship. The rich man is struggling and could use a bit of chizuk himself. The Torah tells: "ומטה ידו" - it can happen that a man becomes poor, "עמך" - together with you. In other words, you are both struggling, both experiencing financial difficulties. Nevertheless, says the posuk: "והחזקת בו" - do your best to help him and through him ("בו"), you will be strengthened as well; "וחי עמך" - Hashem promises that both of you will live comfortably. 

     On this posuk, the Medrash quotes Tehillim (מא-ב): "אשרי משכיל אל דל ביום רעה ימלטהו ה'" - “Praiseworthy is he who looks after the poor; on a day of calamity Hashem will rescue him.” What is the meaning of these words? Says R' Chaim Yossel, the link between "ביום רעה" in this posuk and "וחי עמך" in our posuk is that it does not refer to the “day of calamity” for the one on the receiving end, but rather the troubles of the one who is giving when he is also going through bad times. And yet, this righteous man is praiseworthy for he nevertheless extends aid to the less fortunate even while experiencing his own financial difficulties. For this reason, Dovid HaMelech uses the word "משכיל" (wise) rather than "נותן" (give) because he is acting wisely by helping the poor, for by doing so, he will therefore be strengthened by the Ribono shel Olam together with the poor man.