John 6:37

All that the Father giveth me
The "all" design not the apostles only, who were given to Christ as such; for these did not all, in a spiritual manner, come to him, and believe in him; one of them was a devil, and the son of perdition; much less every individual of mankind: these are, in some sense, given to Christ to subserve some ends of his mediatorial kingdom, and are subject to his power and control, but do not come to him, and believe in him: but the whole body of the elect are here meant, who, when they were chosen by God the Father, were given and put into the hands of Christ, as his seed, his spouse, his sheep, his portion, and inheritance, and to be saved by him with an everlasting salvation; which is an instance of love and care on the Father's part, to give them to Christ; and of grace and condescension in him to receive them, and take the care of them; and of distinguishing goodness to them: and though Christ here expresses this act of his Father's in the present tense, "giveth", perhaps to signify the continuance and unchangeableness of it; yet he delivers it in the past tense, in ( John 6:39 ) , "hath given"; and so all the Oriental versions render it here. And it certainly respects an act of God, antecedent to coming to Christ, and believing in him, which is a fruit and effect of electing love, as is clear from what follows:

shall come unto me;
such who are given to Christ in eternal election, and in the everlasting covenant of grace, shall, and do, in time, come to Christ, and believe in him to the saving of their souls; which is not to be ascribed to, any power and will in them, but to the power and grace of God. It is not here said, that such who are given to Christ have a "power" to come to him, or "may" come if they will, but they shall come; efficacious grace will bring them to Christ, as poor perishing sinners, to venture on him for life and salvation:

and him that cometh to me I will in no wise cast out;
such who come to Christ in a spiritual manner, and are brought to believe in him truly and really, he not only receives kindly, but keeps and preserves them by his power, and will not cast them out, or thrust them from him into perdition: the words are very strongly and emphatically expressed in the original, "I will not, not, or never, never, cast out without"; or cast out of doors. Christ will never cast them out of his affections; nor out of his arms; nor out of that family that is named of him; nor out of, and from his church, which is his body, and of which they are members; nor out of a state of justification and salvation; and therefore they shall never perish, but have everlasting life. The three glorious doctrines of grace, of eternal election, efficacious grace in conversion, and the final perseverance of the saints, are clearly contained in these words.