Perhaps a further rewording of the OP will make it a bit more clear: Whenever the three days and three nights of Matthew 12:40 is brought up in a "discussion" with 6th day of the week crucifixion folks, they frequently assert that it is using common Jewish idiomatic language. I wonder if anyone knows of any writing that shows an example from the first century or before regarding a period of time that is said to consist of a specific number of days and/or a specific number of nights where the period of time absolutely couldn't have included at least a part of each one of the specific number of days and at least a part of each one of the specific number of nights? If it is using common idiomatic language, there ought to be examples of that usage in order to be able to make that assertion.
You can start with Acts 10.
Acts 10:1-30 King James Version (KJV)
10 There was a certain man in Caesarea called Cornelius, a centurion of the band called the Italian band,
2 A devout man, and one that feared God with all his house, which gave much alms to the people, and prayed to God alway.
3 He saw in a vision evidently about the ninth hour of the day an angel of God coming in to him, and saying unto him, Cornelius.
4 And when he looked on him, he was afraid, and said, What is it, Lord? And he said unto him, Thy prayers and thine alms are come up for a memorial before God.
5 And now send men to Joppa, and call for one Simon, whose surname is Peter:
6 He lodgeth with one Simon a tanner, whose house is by the sea side: he shall tell thee what thou oughtest to do.
7 And when the angel which spake unto Cornelius was departed, he called two of his household servants, and a devout soldier of them that waited on him continually;
8 And when he had declared all these things unto them, he sent them to Joppa.
9 On the morrow, as they went on their journey, and drew nigh unto the city, Peter went up upon the housetop to pray about the sixth hour:
10 And he became very hungry, and would have eaten: but while they made ready, he fell into a trance,
11 And saw heaven opened, and a certain vessel descending upon him, as it had been a great sheet knit at the four corners, and let down to the earth:
12 Wherein were all manner of fourfooted beasts of the earth, and wild beasts, and creeping things, and fowls of the air.
13 And there came a voice to him, Rise, Peter; kill, and eat.
14 But Peter said, Not so, Lord; for I have never eaten any thing that is common or unclean.
15 And the voice spake unto him again the second time, What God hath cleansed, that call not thou common.
16 This was done thrice: and the vessel was received up again into heaven.
17 Now while Peter doubted in himself what this vision which he had seen should mean, behold, the men which were sent from Cornelius had made enquiry for Simon's house, and stood before the gate,
18 And called, and asked whether Simon, which was surnamed Peter, were lodged there.
19 While Peter thought on the vision, the Spirit said unto him, Behold, three men seek thee.
20 Arise therefore, and get thee down, and go with them, doubting nothing: for I have sent them.
21 Then Peter went down to the men which were sent unto him from Cornelius; and said, Behold, I am he whom ye seek: what is the cause wherefore ye are come?
22 And they said, Cornelius the centurion, a just man, and one that feareth God, and of good report among all the nation of the Jews, was warned from God by an holy angel to send for thee into his house, and to hear words of thee.
23 Then called he them in, and lodged them. And on the morrow Peter went away with them, and certain brethren from Joppa accompanied him.
24 And the morrow after they entered into Caesarea. And Cornelius waited for them, and he had called together his kinsmen and near friends.
25 And as Peter was coming in, Cornelius met him, and fell down at his feet, and worshipped him.
26 But Peter took him up, saying, Stand up; I myself also am a man.
27 And as he talked with him, he went in, and found many that were come together.
28 And he said unto them, Ye know how that it is an unlawful thing for a man that is a Jew to keep company, or come unto one of another nation; but God hath shewed me that I should not call any man common or unclean.
29 Therefore came I unto you without gainsaying, as soon as I was sent for: I ask therefore for what intent ye have sent for me?
30 And Cornelius said, Four days ago I was fasting until this hour; and at the ninth hour I prayed in my house, and, behold, a man stood before me in bright clothing,
Please pay attention to the TIME element in this narrative for now.
1. V3- Cornelius has a vision about 1500H, sends out his servants the same day
2. V9- they arrive in Joppa the NEXT day around 1200H
3. V23- they lodged and the NEXT day they left for Caesarea
4. V24- they arrived in Caesarea the NEXT day
And finally,
5. V30- Cornelius says he had a vision FOUR days ago. Can we identify these days?
Day #1 would be when Cornelius had a vision at ~1500H and sent off his messengers. Jewish days ended at sunset so the day ended about 4 hours later.
Day #2 would be the day they arrived and lodged at Joppa
Day #3 would be the day they together with Peter left for Caesarea
Day #4 would be the day they arrived
So Cornelius included the very day they arrived in sharing the timing of the vision as a full day together with the day he sent them off.
Let's assume they arrived in Caesarea late in the evening on day 4. You have a period of 72 hours reckoned as 4 days. Now, it's your turn to do the Maths; count for me the number of nights inside these four days.
Please note the narrative has no 'days and nights' idiom. But it serves very important lessons chiefly being a part of a day is regarded as a full day in normal speech.
Now, let's look at a specific example of 'days and nights' idiom.
Esther 4:16, 5:1(KJV)
16 Go, gather together all the Jews that are present in Shushan, and fast ye for me, and neither eat nor drink three days, night or day: I also and my maidens will fast likewise; and so will I go in unto the king, which is not according to the law: and if I perish, I perish....
(KJV) 5 Now it came to pass on the third day, that Esther put on her royal apparel, and stood in the inner court of the king's house, over against the king's house: and the king sat upon his royal throne in the royal house, over against the gate of the house
Please note Esther appeared before the King on the THIRD day. Third from what? The last day of the fasting where she broke the fast of course. Supposing the fast lasted three literal days and nights, and using the Acts 10 method of reckoning days. She would have appeared before the King on the FOURTH day not third. To prove it, let's try counting days inside a three literal days and nights period and tell me when the last day/night would fall. Remember a days starts and ends at dusk.
Supposing the fasting started on Monday morning. Monday morning and night, Tuesday the same and Wednesday. The fasting would end on Thurdsay morning at the earliest. So Thursday is our THIRD day. This makes Wednesday our SECOND day, Tuesday our FIRST day. What do we do with Monday?
But if we reckon 'three days and three nights' to be 3 normal Jewish days, the Monday fast terminates on Wednesday and on the same day she stands before the king
