Whether you are giving or receiving comfort, these books will equip through hard times. (ranked in the order I’d recommend reading them).
Christ and Calamity by Harold Senkbeil
Gentle and Lowly by Dane Ortlund
The Loveliness of Christ by Samuel Rutherford (compiled from his letters which are also excellent)
Valley of Vision by various puritan writers
Walking with God through Pain and Suffering by Timothy Keller
Cultivating Epiphanies 