It states (Yeshayah 28:16) יחיש לא המאמין, which can be translated as, "When one has emunah, he has no worries" (Beis Aharon p.143, quoting Rebbe Asher of Stolin zt'l). When people have emunah, they can be compared to a child who feels secure and confident in his parent's arms. They know they are in Hashem's caring hands, so why worry?
The Chofetz Chaim's son said that his father would often say the words (Shmuel 1, 30:6), אלקיו 'בה דוד ויתחזק, "Dovid strengthened himself in Hashem, his G-d." The pasuk refers to one of the most challenging moments in Dovid HaMelech's life, and perhaps it was even the hardest moment, r'l.
This is what occurred: The Navi tells that at one point in Dovid HaMelech's life, he lived in Tziklag with his two wives, six hundred of his warriors, and their families. At a time of war, Dovid left the city with the six hundred warriors, and when they returned to Tziklag, he discovered that his two wives and the wives of the six hundred warriors and their children were taken hostage.
בהם אין אשר עד ויבכו קולם את אתו אשר והעם דוד וישא אשת ואביגיל היזרעלית אחינעם נשבו דוד נשי ושתי ,לבכות כח נפש מרה כי לסקלו העם אמרו כי מאד לדוד ותצר ,הכרמלי נבל בנתיו ועל בנו על איש העם כל, "Dovid and the people who were with him raised their voices and wept, until they had no more strength to weep. Both of Dovid's wives had been captured... Dovid was very distressed, for the people were ready to stone him, for the souls of all the people were embittered, each over his sons and daughters." The Malbim explains that they wanted to stone him because they felt that Dovid was guilty and had acted irresponsibly. If he had left some of his warriors in Tziklag, they could have protected the women and children.
At this time, Dovid felt alone. He didn't have family to support him (his wives were captured), and he didn't have friends to give him a kind word because everyone blamed him. The situation was dire, as Chazal (Bava Basra 8:) state, מכולן קשה שבי, captivity is the worst. The women and children were in grave danger. מאוד לדוד ותצר, Dovid was very worried and upset.
But even then, אלקיו 'בה דוד ויתחזק, "Dovid drew strength from Hashem, his G-d." He remembered that Hashem was with him, and this gave him strength. He had bitachon that Hashem would help him. He gathered an additional four hundred warriors, attacked his enemies, and brought back home all the hostages. No one was missing. No one was harmed or scathed.
The Chofetz Chaim would often repeat the words אלקיו 'בה דוד ויתחזק because, in all situations, we can attain strength and hope from our bitachon in Hashem.
A Holocaust survivor who lost his children in the war asked the Pnei Menachem zt'l to ask his father, the Imrei Emes zt'l for chizuk, to comfort and console his broken spirit. The Imrei Emes told the Pnei Menachem to write to the survivor this story of Dovid HaMelech in Tziklag. The Imrei Emes said, "Write to him that if he will remain strong, everything will be returned to him."
The Pnei Menachem asked his father, "How can this Holocaust survivor possibly get his children back? The women, children, and wealth taken from Tziklag were returned, but this man lost his children. How can he get his children back?" The Imrei Emes replied in brief, "Write him my answer."
Once, the Pnei Menachem went to be menachem avel a father who lost his son, and the Pnei Menachem told him this story. The Pnei Menachem added, "The truth is that everything will come back. Although we don't understand how it could be, but behold Eliyahu comes to every bris, although we don't see him." The Pnei Menachem was saying that there are things we don't see and that we don't understand, but they are true nonetheless. Somehow, the lost child will return.
At another time, the Pnei Menachem said in his father’s name, the Imrei Emes zt'l, "In the future, we will understand that death is nothing but an illusion." This is because the neshamah lives forever. So it is easier to understand how everything will be returned in the end.
