The Seventh Sunday of the Great Fast (Abiy Tsom) is called Nicodemos, which is named after a member of the Jewish ruling council man who was very impressed with the miracles that our Lord and Savior Eyesus Kristos performed in Jerusalem. He came to him in the night in search of more knowledge and as a result, he learned about the first mystery of the sacraments of the Church, the Sacrament of Baptism.
"There was a man of the Pharisees, named Nicodemus, a ruler of the Jews: The same came to Jesus by night, and said unto him, Rabbi, we know that thou art a teacher come from God: for no man can do these miracles that thou doest, except God be with him. Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.
Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother's womb, and be born?
Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.
Marvel not that I said unto thee, Ye must be born again. The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit.”
According to the teaching of Ethiopian Orthodox Tewahedo Church when the priest prays over the water in the name of the Father, the Son and the Holy Spirit, the water becomes the very same water that came out of the side of Our Lord and Savior Eyesus Kristos. And to Inherit the kingdom of God, as we are born from our father and mother we also need to be born again from God through baptism. Baptism is one of the seven sacraments through which a believer unites with the Holy Spirit and also is accepted into the membership of the Church.
Why the Ethiopian Orthodox Tewahedo Church baptize boys after Forty  days, and girls after Eighty  days?
The Orthodox Churches baptize children on the bases of the faith of the parents and godparents. The Holy Bible teaches us that Christian parents must teach and raise up their children in the way of the Lord.
“Then were there brought unto him little children, that he should put his hands on them, and pray: and the disciples rebuked them.
But Jesus said, Suffer little children, and forbid them not, to come unto me: for of such is the kingdom of heaven.”
This is also based on God's commandment to Moses.
"Speak unto the children of Israel, saying, If a woman have conceived seed, and born a man child: then she shall be unclean seven days; according to the days of the separation for her infirmity shall she be unclean.
And in the eighth day the flesh of his foreskin shall be circumcised.
And she shall then continue in the blood of her purifying for thirty-three days ; she shall touch no hallowed thing, nor come into the sanctuary, until the days of her purifying be fulfilled [7 +33 = 40].
But if she bear a maid child, then she shall be unclean two weeks, as in her separation: and she shall continue in the blood of her purifying for sixty six days [14+66 = 80]."
The Ethiopian Orthodox Tewahedo Church teaches that the reason is Adam was taken into Eden Forty  days after he was created and Eve was taken into Eden Eighty  days after she was made from Adam's rib.
Nicodemus and Joseph had lived as secret disciples of Our Lord and Savior Eyesus Kristos and thus buried his body after he died on the Cross.
“And after this Joseph of Arimathaea, being a disciple of Jesus, but secretly for fear of the Jews, besought Pilate that he might take away the body of Jesus: and Pilate gave him leave. He came therefore, and took the body of Jesus.
And there came also Nicodemus, which at the first came to Jesus by night, and brought a mixture of myrrh and aloes, about an hundred pound weight.
Then took they the body of Jesus, and wound it in linen clothes with the spices, as the manner of the Jews is to bury.”
May Medhanealem Grant us to See The Light of His Resurrection in Peace Amen!