Rashi: You will be saved from plague. We do not find v'Chelach elsewhere in Tanach. It seems that is an expression of full ripening of grain. Chazal said that its Gematriya is 60 [years]. Ibn Ezra (24)- it refers to dying after his full days, i.e. Ziknah ¹ .

Rashi: This is like a stalk is removed from the ground in its time (when it bears its sheaves - Malbim).

Ibn Ezra: This is when it is cut. Alos is like "Al Ta'aleni ba'Chetzi Yamai."

Devar Eliyahu: There are two times of gathering. (a) Before the time - then every seed is moist and full. (b) In its time - then it is dry. So people die - a youth who dies, he is moist and fresh in his strength. This is not in his time. In his time is in old age - his moisture departed. Elifaz said that these two will be done to Iyov. He will come to the grave in his moisture, but it will be in his time. Some live long, but detest old age - Yamim she'Ein Bahem Chefetz. Iyov will die "ka'Alos Gadish b'Ito", in his time, when he should be dry, but he will retain his strength - "uch'Yamecha Dav'echa."