And I spake unto you at that time, saying, I am not able to bear you myself alone:

Wesley's Notes

1:9 At that time - That is, about that time, namely, a little before their coming to Horeb.

Jamieson-Fausset-Brown Bible Commentary

9-18. I spake unto you at that time, saying, I am not able to bear you myself alone-a little before their arrival in Horeb. Moses addresses that new generation as the representatives of their fathers, in whose sight and hearing all the transactions he recounts took place. A reference is here made to the suggestion of Jethro (Ex 18:18). In noticing his practical adoption of a plan by which the administration of justice was committed to a select number of subordinate officers, Moses, by a beautiful allusion to the patriarchal blessing, ascribed the necessity of that memorable change in the government to the vast increase of the population.

Matthew Henry's Concise Commentary

1:9-18 Moses reminds the people of the happy constitution of their government, which might make them all safe and easy, if it was not their own fault. He owns the fulfilment of God's promise to Abraham, and prays for the further accomplishment of it. We are not straitened in the power and goodness of God; why should we be straitened in our own faith and hope? Good laws were given to the Israelites, and good men were to see to the execution of them, which showed God's goodness to them, and the care of Moses.