Pray without ceasing. 1 Thessalonians 5:17

The closet and solitary prayer is a necessary duty, and a profitable one. It does much for the enlargement of the heart. When a man seeks to deal most earnestly with God, he should seek retirement, and be alone. Christ in his agonies went apart from his disciples.

It is notable that when Jacob sought to wrestle with God, it is said, 'And Jacob was left alone' (Gen. 32:24). When he had a mind to deal with God in great earnestness, he sent away all his company. A hypocrite finds a greater flash of gifts in his public duties; but he is slight and superficial when he is alone with God. Usually God's children are able to most affectionately pour out their hearts before him in private. Here, they find their affections free to wrestle with God. Here,
one finds most communion with God, and enlargement of heart. In private we are wholly at leisure to deal with God in a child-like liberty.

Now, will you omit this duty where you may be most free, without distraction, to let out your heart to God? The sweetest experiences of
God's saints are when they are alone with him.

Without seeking God often, the vitality of the soul is lost. We may as well expect a crop and
harvest without sowing, as living grace without seeking of God. God is first cast out of the closet, and then out of the family, and within
a little while, out of the congregation. Omit secret prayer, and some great sin will follow. A man who is often with God, does not dare to offend him so freely as others do. Religion, as it were, dies by degrees. Whatever else is forgotten, God must not be forgotten. Make God a good allowance. Make a prudent choice yourselves, and  consecrate such a part of time as will suit with your occasions, your course of life, and according to your abilities and opportunities.
Thomas Manton, Works, i:13-20