It would be better to omit the words "when I am," which are not in the original. The sign was to be Elisha's seeing the actual translation, which he did 2 Kings 2:12.

A hard thing - This is what is not in my power, God alone can give this; yet if thou see me taken away from thee, it shall be so. Perhaps this means no more than, "If thou continue with me till I am translated, God will grant this to thee;" for on the mere seeing or not seeing him in the moment in which he was taken away, this Divine gift could not depend.

And he said, thou hast asked a hard thing,.... Not a common privilege, but what is rarely enjoyed, and difficult to obtain, few are so favoured of God:

nevertheless, if thou see me when I am taken from thee, it shall be so unto thee, but if not, it shall not be so; meaning, that if his rapture was visible to Elisha, and he was favoured with a sight of his assumption, and be an eyewitness of it, this would be a token both to Elijah that it was agreeable to the Lord to ask of him this favour for him, and to Elisha to expect it, otherwise not.

And he said, Thou hast asked a hard thing: nevertheless, if thou see me when I am taken from thee, it shall be so unto thee; but if not, it shall not be so.

2:10 A hard thing - A rare and singular blessing, which I cannot promise thee, which only God can give; and he gives it only when, and to whom he pleaseth. If thou seest - This sign he proposed, not without the direction of God's Spirit, that hereby he might engage him more earnestly to wait, and more fervently to pray for this mercy.

Thou hast...: Heb. Thou hast done hard in asking

10. Thou hast asked a hard thing-an extraordinary blessing which I cannot, and God only, can give. Nevertheless he, doubtless by the secret directions of the Spirit, proposed to Elisha a sign, the observation of which would keep him in the attitude of an anxious waiter, as well as suppliant for the favor.

2:9-12 That fulness, from whence prophets and apostles had all their supply, still exists as of old, and we are told to ask large supplies from it. Diligent attendance upon Elijah, particularly in his last hours, would be proper means for Elisha to obtain much of his spirit. The comforts of departing saints, and their experiences, help both to gild our comforts and to strengthen our resolutions. Elijah is carried to heaven in a fiery chariot. Many questions might be asked about this, which could not be answered. Let it suffice that we are told, what his Lord, when he came, found him doing. He was engaged in serious discourse, encouraging and directing Elisha about the kingdom of God among men. We mistake, if we think preparation for heaven is carried on only by contemplation and acts of devotion. The chariot and horses appeared like fire, something very glorious, not for burning, but brightness. By the manner in which Elijah and Enoch were taken from this world, God gave a glimpse of the eternal life brought to light by the gospel, of the glory reserved for the bodies of the saints, and of the opening of the kingdom of heaven to all believers. It was also a figure of Christ's ascension. Though Elijah was gone triumphantly to heaven, yet this world could ill spare him. Surely their hearts are hard, who feel not, when God, by taking away faithful, useful men, calls for weeping and mourning. Elijah was to Israel, by his counsels, reproofs, and prayers, better than the strongest force of chariot and horse, and kept off the judgments of God. Christ bequeathed to his disciples his precious gospel, like Elijah's mantle; the token of the Divine power being exerted to overturn the empire of Satan, and to set up the kingdom of God in the world. The same gospel remains with us, though the miraculous powers are withdrawn, and it has Divine strength for the conversion and salvation of sinners.