Haftarah for Haazinu
As you may be aware, King David composed Tehillim, the Book of Psalms. Throughout all the trials that he endured in his life, whether being pursued by Saul, his family being abducted, a baby dying, one of his children raping another then being murdered by a third, being driven from his throne, etc., etc., etc., he always remembered to ask G-d for help, to thank Him and to praise Him. We heard some of David's songs earlier in the Book of Samuel; here we have an example of one that would be included in Psalms, with some minor edits, as Psalm 18. The version included here was David's "personal" version, sung by him as a Psalm of thanks in times of victory. The version included in Psalms is intended for posterity, for all people to sing to G-d about salvation from their troubles in life.
In this Psalm, David calls G-d his protector, in Whom he takes refuge. When threatened with death, David calls upon G-d, Who hears and answers him. David alludes to the way G-d answered the Jewish people when He redeemed them from Egypt, enveloping the oppressors in darkness and splitting the Red Sea. David then thanks G-d for personal kindnesses, such as enabling him to defeat foes who were mightier than himself. David credits much of his success to his refusal to kill Saul when the opportunity presented itself, because G-d rewards righteousness and punishes sin. With G-d's help, David says that he can defeat any foe and overcome any obstacle. David pursued his enemies and defeated them; G-d even saved David from Jewish foes, such as Saul, Doeg and Achitofel, among others. David conquered foreign lands and they yield to him. For all this, David praises Hashem and ascribes his successes to Him; He is the Source of strength to him and his descendants forever.
Probably the most striking difference between this chapter and the way David's song appears in Psalm 18 is the last verse, which we say at the end of bentching (birkas hamazon, grace after meals). Here it reads, "migdol yeshuos malko," G-d is the tower of His chosen king's salvations. The corresponding verse in Psalms says "magdil yeshuos malko," that G-d increases His chosen king's salvations. For his personal praise, David used the word migdol - tower - referring to his complete salvation. For the "public" version in Psalms, he used magdil - increases - referring to gradual growth leading towards the ultimate salvation. On weekdays, we bentch using magdil - gradual growth. On Shabbos, which is a taste of the "World to Come," we bentch with the word migdol, reflecting the completion of our salvation.