As a little boy I have seen mother hens protecting their little chicks. The chicks are small balls of flesh and feather that so tender that looks like fur on them. They will be around the mother exploring their world and gobbling worms mother has found for them and chirping happily. It is a noisy scene. As soon as the mother hen detects the presence of a predator bird it makes a particular sound. It is a warning and the little chicks run to find shelter under the wings of their mother. The mother sits firmly on the ground protecting her little chicks who has sought shelter inside her wings. There is absolute silence; not a single chick dares to make a sound. Singing under the wings is dangerous! Moreover, it takes a lot of courage to do that when the predator bird is still hovering over.
One of the powerful imageries of the Bible is that of God as the mother hen who protects his children under his wings in times of trouble. Boaz uses this imagery when he talks about Ruth joining the people of Israel. He said, "Yahweh recompense your work, and a full reward be given you of Yahweh, the God of Israel, under whose wings you are come to take refuge" (Ruth 2:12). Psalmists used this imagery when they prayed to God for protection: "Keep me as the apple of your eye; Hide me under the shadow of your wings..." (Psalms 17:8; See also Psalm 36:7; Psalm 57:1; Psalm 61:4).
However, the Psalmist in 63:7 is different. He says, "Because you are my help, I sing in the shadow of your wings" (Psalms 63:7). (Some translations may have "rejoice" but the word here means "singing for joy".) He is rather a very bold chick. He sings while hiding himself under the wings of God, his mother and protector. Any chick should know that singing while under the wings is dangerous. Silence is number one safety rule.
The psalmist stretches the imagery a little beyond the real situation to make a statement of faith. The chicks find shelter under the wings of the mother out of fear. They remain under the wings of the mother out of fear. However, they are safe, there is nothing to fear. They are silent out of fear though no predator can snatch them out of the security of the mother's wings. Then why not sing? It requires some trust in their mother's power to protect them. That is what exactly the psalmist feels knowing God as his "helper".
A joyful Christian life proceeds from a trust in God's power to protect us. Disciples of Christ can be joyful at all times, even at the most dangerous moments of life if they know under whose wings they have found shelter.